BB
Lysogenic Cycle
"A type or phase of the virus life cycle during which the virus integrates into the host chromosome of the infected cell, often remaining essentially dormant for some period of time" lysogenic cycle is the dormant cycle of the virus during which time viral DNA is incorporated into the host's genome but new viruses are not being assembled. This would be equivalent to HIV infection without AIDS symptoms, or to the presence of the herpes virus in the DNA of the host without any current cold sores or other symptoms.
Molecular Cloning: Sticky Ends
"sticky ends" are so named because the endonuclease cuts the DNA in a staggered fashion that leaves one side of the helix longer than the other. The specific base sequence recognized by the endonuclease is called the recognition sequence.
Ethanol Fermentation
(primarily yeast, a few bacteria) Ethanol is produced and is the final electron acceptor. Ethanol fermentation is unique compared to lactic acid fermentation in that the carbon skeleton changes. Pyruvate (3C) is broken down into ethanol (2C) and CO2.
Allosteric Enzymes
- Enzymes whose activity is influenced by the reversible, non-covalent binding of another molecule. This could be a second subunit of the same enzyme, or it could be an activating or deactivating molecule. Threonine deaminase is an allosteric enzyme. It is inhibited by isoleucine, and it has two binding sites for it, one low affinity and one high affinity. When isoleucine binds the high affinity site, the binding affinity for the low affinity site increases. When isoleucine binds the low affinity site, the enzyme is deactivated. So enzyme activity is affected by non-covalent binding of isoleucine, initially by altering the binding affinity in the inhibition site, and then by actually being inhibited by the inhibitor.
Positive Feedback
- the product of a reaction acts as an agonist for the reaction. For example, the product could itself be an activator of the reaction, so that the more product you have in solution, the more likely the reaction will happen. (think of connection with dishabituation) The product could also be part of the synthesis pathway for the substrate, so that the more product you have, the more substrate will be made, increasing the forward reaction. Positive feedback is relatively rare in the human body, but it does exist. In blood coagulation, upon damage to a blood vessel, the glycoprotein FVII is released. An activation cascade of coagulation factors occurs, resulting in prothrombin being activated to thrombin. Thrombin activates FVII, resulting in an increase to the activation cascade, leading to more thrombin. Negative feedback is much more common,
Resting Potential
-70 mV. The voltage across the membrane when an action potential is NOT present (e.g., one has not yet occurred, or it has already passed). Know the exact value: -70 mV
Pyranose vs Furanose
...Five-membered rings are called "furanoses" and six-membered rings are called "pyranoses".
Joint Types
1) Fibrous (skull bones) 2) Cartilaginous (pubic symphysis, intervertebral discs) 3) Synovial (knee, elbow, etc.)
Fructose Metabolism at the Liver
1) Fructokinase converts Fructose -> Fructose-1P 2) Fructose-1-phosphate aldolase converts Fructose-1P -> Glyceraldehyde-3P + Dihydroxyacetone-P (DHA-P) 3) Triose phosphate isomerase converts DHA-P -> Glyceraldehyde-3P (GA-3P is then funneled into the 5th step of GLY)
diploid
2n chromosomes Diploid cells have two copies of each chromosome, one from mom and one from dad The value of n varies among species, for humans it is 23, therefore all human diploid cells, being 2n, have 46 chromosomes.
Ketone Bodies
3 types= Acetone (no energy), Acetoacetate (energy), and 3 Hydroxybutrate (energy) Formed in the liver in fasting periods then there is alot of products in fatty acid metabolism 2 out of the 3 are used for energy by the herat and brain in fasting periods Ketone bodies are not used by the liver due to lacking a necessary enzyme Lots of ketone bodies= Ketoacidosis, excess acidity of blood
Pyranose vs Furanose
6 membraed ring vs 5 membered ring
Nervous Tissue
A body tissue that carries electrical messages back and forth between the brain and other parts of the body. the neurons of the central and peripheral nervous systems glial cells—astrocytes, microglia, Schwann cells, oligodendrocytes, and ependymal cells—are also considered nervous tissue. Ependymal cells are unique because you could clearly argue that they are both epithelial and nervous. brain, spinal cord, neurons
Muscle Tissue
A body tissue that contracts, or shortens, making body parts move. Muscle tissue is easy to classify: it is skeletal, cardiac, or smooth. cardiac muscle, smooth muscle, skeletal
Mutations:
A change in the nucleotide sequence of an organism's DNA, ultimately creating genetic diversity. Mutations also can occur in the DNA or RNA of a virus. A mutation is any change in the DNA sequence
Mendelian Genetics: Gene
A gene is a segment of DNA that codes for a protein
Mendelian Genetics: Locus
A locus is the specified physical location of a gene on a chromosome.
Epididymis
A long, coiled duct on the outside of the testis in which sperm mature. Location of sperm where they are nurtured, fully matured, and stored until ejaculation
Strecker Synthesis
A method of synthesizing amino acids that uses condensation between an aldehyde and hydrogen cyanide, followed by hydrolysis.
Mutations: Missense
A missense mutation is a mutation that changes the codon so that a different amino acid will be incorporated
Skeletal Muscle Anatomy
A muscle group= bundle of fasciculi Each fasicle is a bundle of many long muscle fibers Around each muscle has a special cell membrane called the sarcolemma Each muscle have many nuclei aka multinucleated The volume of each cell is filled with myofibrils, small round tubes, these myofibrils are long proteins compsoed of actin and myosin fibers. Actin and myosin fibers create repeating units called sarcomeres Bundles of myofibrils are interwoven among portions of the muscle cell's endoplasmic reticulum called the Sarcoplasmic reticulum --- SR stores and releases Ca2+ to initiation contraction sequence
Evolution & Populations: Niche
A niche is the very specific status or role an organism plays in its ecosystem. It can also refer to a specific habitat occupied by one organism within its ecological community.
Absolute Refractory Period
A period of time following an action potential during which no additional action potential can be evoked regardless of the level of stimulation. (usually because Na+ channel closed whle K+ efflux) The absolute refractory period is a portion of time during which an action potential cannot be initiated regardless of the strength of the stimulus. This time period occurs during the progression of a previous action potential. The progression of an action potential involves the depolarization of the membrane and a second stimulus cannot be initiated until the membrane is repolarized.
Reducing Sugar vs Non-reducing Sugar
A reducing sugar is one that is capable of reducing another molecule through an oxidation-reduction reaction (the sugar will become oxidized). To be able to participate in a redox reaction, the sugar must have an openchain form that has a free aldehyde group, and so it must be an aldose. Some ketoses are also reducing sugars, if they can isomerize to contain an aldehyde group. However, in that case, it is the aldehyde isomer and not the ketose form that is a reducing sugar. Disaccharides in which one of the subunits can linearize into an aldehyde are also reducing sugars. A non-reducing sugar is one that cannot participate in a redox reaction to reduce another molecule. To recognize a reducing sugar, look for an aldehyde group. The carbon with the double bonded oxygen should have a hydrogen attached in chain form. In ring form, the ring oxygen should be connected to one carbon with an R group attached and one carbon with an OH attached.
Isotonic Solution
A solution in which the concentration of solutes is essentially equal to that of the cell which resides in the solution
Hypertonic Solution
A solution in which the concentration of solutes is greater than that of the cell that resides in the solution
Hypotonic Solution
A solution in which the concentration of solutes is less than that of the cell that resides in the solution
Mendelian Genetics: Test-cross
A test cross is a cross between a homozygous recessive individual and an individual with a dominant phenotype for whom the genotype is uncertain (could be TT or Tt). If the dominant individual was TT then all offspring of the test cross will have the dominant phenotype (all will be Tt). However, if the dominant individual was a heterozygote then half would have the dominant phenotype (genotype Tt) and half would have the recessive phenotype (genotype tt
mRNA
A type of RNA, synthesized from DNA, that attaches to ribosomes in the cytoplasm and specifies the primary structure of a protein; also called messenger RNA. the complementary RNA strand copied from the DNA template strand. The original copy is called pre-mRNA because it contains many non-coding introns and lacks the poly-A tail and 5' cap. After it is fully processed and ready for translation it is called mature mRNA.
Bacteria: Transduction
A virus transfers bacterial genes Viruses accidentally incorporate host genetic material into their nucleic acids.
Lyases
AB <-> A + B [cleavage/synthesis; NO H2O, NOT hydrolysis] an enzyme that catalyzes the joining of specified molecules or groups by a double bond. catalyze cleavage without the addition of water and without the transfer of electrons
Consumption of ATP: Phosphoryl Group Transfers
ATP -> ADP + Energy Phosphate is transferred onto another molecule rather than being released as Pi Substrate level phosporylation, usually uses an enzyme such as a kinase IT is done in this rxn: Glucose + ATP -> Glucose-6-Phosphate + ADP (during glycolysis)
Active Transport
ATP required Energy-requiring process that moves material across a cell membrane against a concentration difference Good example- resting memebrane potential
Citric Acid Cycle Carbon Skeleton
Acetyl CoA + Oxalocacetate-> Citrate-> Isocitrate-> Alpha-Ketoglutarate-> Succinyl CoA-> Succinate-> Fumarate-> Malate -> Oxaloacetate Isocitrate->Alpha Ketoglutarate= Nad+→ NADH +H+, CO2 Alpha Ketoglutarate-> Succinyl CoA= NAD+, CoA → NADH + H+ + CO2 Succinyl CoA-> Succinate= GDP + Pi→ GTP + CoA Succinate-> Fumarate= FAD→ FADH2 Malate-> Oxaloacetate= NAD+ → NADH + H+ Oxaloacetate→ Citrate = H2O + Acetyl CoA→ CoA
Microfilaments
Actin Polymers Microfilaments form thin filament portion of sarcomere In addition to their role in the cytoskeleton, microfilaments form the "thin filament" portion of the sarcomere. The thin filaments act as tracks along which the thick filaments (which are made of myosin motor proteins) move during contraction
ADH
Acts on the collecting duct to make it permeable to water. It causes water retention and increased blood pressure. As the collecting duct passes by the highly concentrated medulla, the ADH thus allows water to permeate through the collecting duct into those areas. This is when our urine becomes REALLY CONCENTRATED!
Aldosterone
Acts on the distal tubule to cause increase in sodium uptake and reabsorbing of Na+ from the collecting duct through protein channels (Na+ and K+ channels). It causes water to flow out by following the sodium molecules to the cells. The net effect is water retention and increased blood pressure to fight against the effects of low blood pressure
Evolution & Populations: Adaptive Radiation
Adaptive radiation is the rapid formation of a variety of species from one ancestral species—usually characterized by a strong environment-species connection. An example would be: if one species of turtle immigrated to five different environments and rapidly formed five different species based on natural selection driven by the unique characteristics of each environmen
Ligases
Addition or synthesis of LARGE molecules, usually ATP-dependent (e.g., DNA Ligase) catalyze addition or synthesis reactions, generally between large similar molecules, and often require ATP
Hematopoiesis
All blood cells develop from stem cells (undifferentiated cells) in the bone marrow;
Bone Marrow
All erythrocytes and leukocytes are made in the red bone marrow via hematopoiesis. Yellow bone marrow is primarily adipose tissue and does NOT produce blood cells. B lymphocytes mature in the bone marrow, while T lymphocytes migrate to the thymus to mature.
PNS
All neurons outside of the CNS; both sensory and motor neurons. Contains "somatic" and "autonomic" subdivisions.
Mendel's Laws: Law of Segregation
Alleles segregate independently of one another when forming gametes.
Allosteric Regulation
Allosteric Enzymes- Enzymes that change conformation or affinity for substrate after binding to the allosteric regulator molecule Allosteric Regulation is when enzymes upregulate or down-regulate activity. Allosteric effects almost ALWAYS resuts form CONFORMATIONAL CHANGES Allosteric Regulator Molecules always bind AWAY FORM THE ACTIVE SITE- the effect is a change in the enzyme itself,NOT inhibition by competing with the substrate for the active site. It does not do competitive inhibition, it simply changes the entire enzyme itself.
Schwann Cells and Myelin Sheaths
Along the axon are specialized neural support cells called Schwann cells. These cells contain high levels of fat and wrap themselves around the axon multiple times creating an insulating myelin sheath.
General Amino Acid Characteristics
Alpha-Carbon STereo Center- ALl human amino acids, except one, chiral at alpha carbon due 2 an R Group, H, carboxylic acid, and amine Absolute COnfiguration- All amino acids are L- or D-, DEPENDS ON IF THE AMINE GROUP IS ON THE L- LEFT OR D- RIGHT ON THE FISCHER PROJECTION -- ALl human amino acids are L-Amino Acids -- L and D are not directly correlated with R and S, seperate stereochemical --For amino acids, L and D refer to the glyceraldehyde molecule that the amino acid could theoretically be synthesized from (D-glyceraldehyde or Lglyceraldehyde)
Sodium/Potassium Pump
An ATP pump that actively transports 3 Na+ ions out of the cell and 2 K+ ions into the cell per cycle. The net effect is more positive charge outside the cell and a progressively more negative charge inside the cell.
tRNA
An RNA molecule that functions as an interpreter between nucleic acid and protein language by picking up specific amino acids and recognizing the appropriate codons in the mRNA The molecule that bridges the gap between mature mRNA and the assembled protein. Each tRNA has an anti-codon on one end and the other end is covalently bonded to the amino acid associated with that anti-codon (or more precisely, the codon that is complementary to the anti-codon)
Pancreatic Amylase
An enzyme secreted by the pancreas into the small intestine that digests any remaining starch into maltose.
Lipase
An enzyme secreted in the digestive tract that catalyzes the breakdown of fats into individual fatty acids that can be absorbed into the bloodstream
Evolution & Populations: Evolutionary Bottleneck
An evolutionary bottleneck is a sudden decrease in the number of individuals in a population.
Zymogen
An inactive precursor of an enzyme, activated by various methods (acid hydrolysis, cleavage by another enzyme, etc.) A protein that is an inactive precursor of an enzyme
Chemotroph
An organism that relies on a chemical source of energy (such as ATP) instead of light (which phototrophs). Chemotrophs oxidize organic or inorganic compounds to harvest energy
Phototroph
An organism that utilizes light as its primary energy source. Phototrophs can capture their own energy directly from the sun via photosynthesis.
Antigen Presentation
Antigen presentation is the process by which a cell that has engulfed an antigen or microbe, (via receptor-mediated endocytosis or phagocytosis) takes protein segments of that microbe, and "presents" them on MHC (Major Histocompatability Complex) proteins embedded in its own cell membrane. This makes the engulfed antigen/foreign proteins available for other cells to "see." Macrophages, dendritic cells, and B-cells "present" antigens in this way. Other cell types also have minor antigen presentation capabilities, but do not play a major role in immune system function.
MCAT rule with Linkage
As far as the MCAT is concerned, any variance from expected ratios or random assortment suggests linkage. For example, in a dihybrid cross you should get a 9:3:3:1 phenotypic ratio and in a monohybrid cross you should get a 3:1 phenotypic ratio. Anything other than these ratios is evidence of some form of linkage. In reality, any number of non-Mendelian factors could be at play, but based on previous AAMC questions it is clear that when an unexpected result is obtained you had better think: LINKAGE!
Quaternary Protein STructure
Association of Multiple Folded proteins into a multi-subunit complex All about how polypeptide chains come together to form the complex/ arrangement of multiple peptide chains. The binding between multiple polypeptides.
Telophase I
At each pole, during this stage, there is a complete haploid set of chromosomes (but each chromosome still has two sister chromatids). A cleavage furrow appears, and by the end of this stage the parent cell has divided into two daughter cells. This separation of the cytoplasm is called cytokinesis
Bacterial Shape: Bacilli
Bacilli are rod-shaped bacteria
Bacteria: Transformation
Bacteria pick up DNA from the environment.
Bacteria Growth
Bacterial colonies grow exponentially, doubling each generation. However, there is a limit to colony size as food and resources decrease and waste accumulates.
Bacteria: Conjugation
Bacterial conjugation is the transfer of genetic material between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells. One bacteria must have an F plasmid (F+); the F plasmid is a plasmid containing the gene for a sex pilus. The recipient can be (F-).
Bacteriophage
Bacteriophages, the viruses that infect bacteria, have very specific components. Bacteriophages always include a capsid head, a tail, and tail fibers A virus that infects bacteria
p I basic
Basic Amino Acids average of pKa- amine group and pKa- basic R group
How many chromosomes do humans have in the following phrases: a) before replication, b) after replication, c) during interphase, d) before S-phase, e) after S-phase, f) in a diploid cell, g) in a haploid cell.
Before Replication-46 After Replication-46 During Interphase-46 Before S-Phase-46 After S-phase-46 In a Diploid Cell-46 In a haploid cell-23
Cellulose
Beta-Linked glucose polymer, used for energy stroage in plants indigestible to animals without help from symbiotic bateria
Enzymes
Biological Catalysts Enzymes are proteins Catalyst vs Enzyme- ---Both increase the rate of rxn by lowering Ea Energy, but enzymes are organic and ctalysts are inorganic. Neither are consumed during the rxn and can be used again. ENzymes are highly specific and catalysts are universal. Catalysts are often metal ions or small molecules. Rxns with enzymes are much faster than catalysts. ALL ENYZMES ARE CATALYSTS, but NOT ALL CATALYSTS ARE ENZYMES. How do enyzmes affect each of the following? reaction rate: - Increase energy of activation: - Lowers activation energy Equilibirum: -Does not affect equilibrium Keq: -NO affect Yield: -NO affect Percent yield: -NO effect.
Hematopoiesis
Blood cell formation the formation and differentiation of blood cells in the bone marrow. Th e flowchart given previously to illustrate the source of immune system cells demonstrates hematopoiesis
Systemic Circulation
Blood flows from the left ventricle, through the arteries, arterioles, capillaries, venules, veins, vena cava and back to the right atrium. Arteries are always away from the heart and veins always towards the heart
Bowman's Capsule
Bowman's capsule is a spherical enclosure around the glomerulus that catches the filtrate as it is formed and funnels it into the proximal tubule
Glycogen
Branched, alpha-linked glucose polymer, used for energy storage in animals
Dendrites
Branchlike parts of a neuron that are specialized to receive information. A dendrite is a finger-like projection from the cell body that receives signal information from an upstream neuron with which it forms a synapse. The signal will be received from the previous neuron via binding of a neurotransmitter on the dendrite portion of the membrane (i.e., postsynaptic membrane).
Absorption- Carbohydrates
Carbohydrates: Digestion begins in the mouth (salivary amylase), and is complete by the time the food has passed through the small intestine. Carbohydrates are broken down entirely to their monomers (e.g., glucose, fructose, etc.) before absorption; they enter the blood stream (NOT the lacteal) and travel to the liver via the hepatic portal vein.
Efferent Neurons (Motor)
Carry signals to a muscle or gland to respond to the stimulus.
Evolution & Populations: Carrying Capacity
Carrying capacity is the maximum number of individuals an ecosystem or environment can sustain
Multipotent
Cells can develop into more than one cell type, but are further differentiated and more limited than pluripotent cells; adult stem cells and cord blood stem cells are considered multipotent.
Totipotent
Cells can give rise to all of the cell types in the body, including extraembryonic or placental cells. Embryonic cells within the first few cell divisions after fertilization are the only cells that are totipotent.
Lipids
Class of biomolecules with inexact definitions Fats, oils, waves, sterols, fat-soluble vitamins, glycerides (mono, di, tri), phospholipids, terpenes MCAT focuses on 2 major identifying characteristics of Lipids 1) Lipids are biomolecules ( meaning made up of different parts) 2) Lipids are hydrophobic (think of oil and water, phospholipid bilayer of membranes, etc)
non-Mendelian inheritance patterns: co-dominance
Co-Dominance is the case in which both phenotypes are fully-expressed at the same time in a heterozygote. In the flower example this could mean that RR gives red flowers, rr gives white flowers, and Rr gives red-and-white striped flowers. Antigens on human red blood cells are another example. A person with the genotype AB does not have a blend of the A and B antigens, they have BOTH A and B antigens
Symbiosis: Commensalism
Commensalism is symbiosis in which one participant benefits and the other participant's experience is neutral— neither beneficial nor harmful
Nervous System
Communication between cells via electrical potentials carried on neurons. Notice, however, that these often involve cascades too. Neurotransmitters bind to receptors on the postsynaptic membrane which initiates a signaling cascade.
Axon Hillock
Cone shaped region of an axon where it joins the cell body. This region has ATON of high concentration of voltage-gated sodium channels. This makes it both sensitive to action potentials and capable of regenerating a strong action potential for transmission down the axon.
Interneurons
Connect afferent and efferent neurons. They also transfer and process signals. The brain and 90% of all other neurons are interneurons.
Sarcomere
Contractile unit of muscle The unit of muscle contraction. Sarcomeres are bounded by Z lins, to which thin filaments attach. Thick filaments are found in the center of the sarcomere, overlapped by thin filaments over one another during contraction reduces the distance between Z lines, shortening the sarcomere. thick filament, thin filament, actin, myosin, myosin heads, A band, I band, H zone, Z line and M line
Convergent Evolution
Convergent evolution results when two species arrive at a point where they have similar functional forms, but they have developed those similar forms via different evolutionary pathways. For example, the last common ancestor between bats and birds did not have wings, so wings are not part of their shared evolutionary connection. Therefore, it must be convergent evolution
Hormonal Control: Glucocorticoids
Cortisol is most important example From the adrenal cortex in response to ACTH from A. Pituitary, it creates a glucagon like effect on metabolism. Stimulates gluconeogensis, glycogenolysis, fatty acid oxidation. Glucocorticoids Reduce inflammation Also enhances emotional memory!
Trypsin
Cuts proteins on the carboxyl side of specific amino acid residues Arginine, Lysine
Chymotrypsin
Cuts proteins on the carboxyl side of specific amino acid residues W, F, Y Chymotrypsin
Hemiacetals vs Hemiketals
Cyclical aldehydes vs cyclical ketones
Mitochondria
DNA in mitochondria is circular Mitochondria have their own DNA and variations to the nuclear genetic code; mitochondrial genes are passed down through the maternal line only. intermembrane space will be more acidic (lower pH) because of the hydrogen ion gradient across the inner mitochondrial membrane. If there was a proton channel that led to the inner mitochondria membrane via disease that distrupts the H gradient, ATP wouldn't be produced
Nucleus
DNA located here, DNA can't leave nucleus A small amount of non-nuclear DNA is found in the mitochondria, it's not NUCLEAR DNA. It's different: haploid, maternal copy only, diploid, structured differently Nucleolus- Site of rRNA transciprtion and ribosome assembly Double bilyaer membrane, one part with ER There are 6 layers overall, cell membrane (2), Nuclear membrane (2), inner nuclear membrane (2), total of 6 single layers of lipids
The Cardiovascular System
Deliver oxygen and nutrients to the cells and tissues of the body; pick up CO2 and waste products and deliver them to the lungs and kidneys
Q28 Ribose and Deoxyribose
Deoxy= without Oxygen or without Hydroxyl group
Osmosis
Diffusion of water through a selectively permeable membrane
Absorption-Lipids
Digestion begins in the small intestine (duodenum) and is complete by the end of the small intestine. Digestion of lipids CANNOT begin prior to their reaching the small intestine where they encounter bile and lipase, the substances capable of beginning the process. Triglycerides are broken down to fatty acids, transported across the membrane, then reformed into triglycerides. Lipids enter the lacteals (NOT the blood stream). In order to travel in blood or lymph, all lipids must either 1) bind to a protein carrier such as albumin or 2) be formed into a chylomicron or micelle.
Leukocytes
Do not contain hemoglobin. These are normal cells, with all their organelles, that are involved in the immune system
Hormonal Control: Catecholamines
Dopamine, Epinephrine, Nor-epinephrine Dopamine= CNS neuro Transmitter Epinephrine (adrenaline) and nor epinephrine= 2 metabolic hormones Have glucagon effect, but most important is RAPID MOBILIZATION OF ENERGY STORES NECESSARY FOR FIGHT OR FLIGHT RESPONSE.
Platelets
Drops of cytoplasm that are sticky if it is exposed to injured epithelium and non-sticky to health epithelium. When it encounters injuries, it releases chemicals that activate other platelets and clotting factors. These platelets come from megakaryocytes that are in the bone marrow.
Urethra
Duct through which urine is discharged.
Chromosomal Mutations:
Duplications (non-disjunction) Deletions (non-disjunction) Translocations Inversions mutations that affect a group of genes or an entire chromosome
3 Germ Layers
Ectoderm: epidermis, nails, tooth enamel, lens of the eye, pituitary gland, central, peripheral and autonomic nervous systems. Mesoderm: dermis, muscle, bone, connective tissues, kidneys, genitalia and most internal organs EXCEPT the liver and pancreas. Endoderm: the entire digestive tract, thyroid, parathyroid, urinary bladder, the lining ONLY of the lungs, the liver and pancreas.
Morula
Eight-celled zygote A solid ball of cells that makes up an embryo; in humans, this stage occurs within four days of fertilization.
Carbohydrates
Empirical Formula of all monosaccharides- (CH2O)n, polysaccharides= Cn(H2O) NOmenclature and CLassification - (-ose) ending is given to all sugars - deoxy- prefix used if normal location of an -OH group is replaced with hydrogen -Aldose vs. Ketose (aldehyde vs ketone) Look at amino acid/ carbohydrate cards for common-named sugars for MCAT 2015
D-GLucose vs L-Glucose
Enantiomers, same molecule, different stereochemistry L, left, furthest -OH from carbonyl is to LEFT in fisher projection D= furthest -OH group from carbonyl to the right RIGHT in Fischer Projection When asked about R/S, rank substitutents and assign R or S If asked for D- or L-, DRAW A FISCHER PROJECTION Same molecule, different stereochemistry at the last chiral carbon
Over The HILL- Enzymes
Enzymes help reactions overcome the energy of activation O-xidoreductases v e r T-ransferases h e H-ydrolases I-somerases L-yases L-igases
Mechanisms of DNA Repair: Mismatch Repair System:
Enzymes that scan newly copied DNA and locate, excise, and replace mismatched base pairs missed by the proofreading of DNA polymerase
Essential vs. Non-Essential Amino Acids:
Essential- Body can't synthesize it, most ingest it Non-Essential- Body can synthesize this amino acid on it's own
Evolution & Populations: Evolution
Evolution is defined as any change in the allelic frequency within a given gene pool across generations
Nucleotide
Examples are DNA and RNA, cAMP, NADH, FADH2, FMN, Coenzyme A, ATP, GTP, UTP, etc 3 Components: Triphosphate, sugar, base Bonds: Phosphodiester bonds Elements: Phosphase, ribose 5' carbon sugar, and a base Connectivity-5' carbon rise of ribose sugar binds with initial phosphate, in a polymer chain, third phosphate would also be bound to 3 carbon of previous ribose sugar
Mechanisms of DNA Repair: Nucleotide Excision
Excision of an oligonucleotide that includes several bases on either side of the error. DNA polymerase and ligase replace the missing segment.
Post-transcriptional Processing
Exons = exit the nucleus (coding sequences retained in mature mRNA) Introns = stay inside the nucleus (noncoding sequences spliced out) Alternate Splicing: Alternative splicing refers to the fact that after introns are removed from the mRNA transcript, the exons can be assembled in any of a number of different orders—each variation resulting in a different protein. Prokaryotes don't do this, they don't have the necessary mechanisms, they go directly from DNA to mRNA without splicing anything out. -This process is often cited as an explanation for how eukaryotes produce an almost unfathomable number of antibodies from relatively few genes.
Protein Separation Techniques: Isoelectric Point
Explain Conceptually, Including Drawings or figures, the process of separating proteins: Isoelectric Point A gel is created with stable pH gradient. A protein in a region of the gel with a pH lower than its isoelectric point will be positively charged (because it will be fully protonated) and so will move toward the negative cathode. A protein in a region with a pH higher than its isoelectric point will be negatively charged (because it will be fully unprotonated) and so will move toward the positive anode. As the protein moves through increasing pH in the gel, the protein's charge will decrease until it reaches the pH of its pI, at which point it will become neutral. At this point the protein will cease to move through the gel, because it has no charge and so has no pull toward either electrode. This causes proteins to form very sharp bands at the pH equal to each protein's pI.
Creation and Propagation of the Action Potential
FREAKING IMPORTANT ON THE MCAT
Vitamins
Fat Soluble- A,D, E, K - Goes directly into the cell without the need for a secondary messenger system or g protein system Water Soluble- All the rest - Requires a secondary messenger system.
Fertilization
Fertilization usually occurs in the Fallopian tubes. Sperm and egg, traveling toward one another, generally meet here. Implantation normally occurs in the uterus, but can occur in the fallopian tubes, leading to a "tubal" or "ectopic" pregnancy.
Inflammatory Response
For the MCAT, we will stick to general basics. First, macrophages, mast cells and dendritic cells are residents of nearly all tissues. When damage is caused—by injury, bacterial invasion, etc.—these cells are activated to release chemicals such as histamines, leukotrienes, and prostaglandins. These chemicals increase blood flow to the injury site, creating heat and redness. These chemicals also increase the permeability of veins and lymph vessels. This causes plasma and interstitial fluid to flood the infection site, resulting in swelling (a.k.a., edema). This swelling and increase in chemicals lead to the pain associated with inflammation as well. Neutrophils are recruited via chemotaxis in very large numbers to the inflammation site.
spindle fibers
Fully formed spindle attach to the sister chromatids from opposite poles
The Digestive System
Function: Mechanically and chemically digest food into monomers and simple components for absorption, sources of energy, carbon chains, and amino acids Physical Digestion= Chewing (mastification) churning in stomach, breaking of food into smaller pieces, emulsification) Chemical Digestion= Breakdown of food that invloves breaking of bonds using digestive enzymes (ex- trypsin)
Microvilli
Further, each epithelial cell lining a villus contains fingerlike projections of the cell membrane called microvilli. To be clear, a villus is an undulation of the lining of the small intestine, while a microvillus is an undulation of the cell membrane of a single cell. Fingerlike extensions of plasma membrane of apical epithelial cells, increase surface area, aid in absorbtion, exist on every moist epithelia, but most dense in small intestine and kidney, for individual cells
Go Phase is of particular significance
G0 phase become "non-proliferative," meaning they are not actively dividing and may not divide in the future. This is sometimes called "rest phase." Many fully differentiated eukaryotic neurons remain in this phase indefinitely. The G0 phase is of interest to MCAT examinees because fully differentiated neurons and cardiac muscle cells are frozen in G0 and do not divide. Multi-nucleated skeletal muscle cells can also be considered to be in the G0 phase. You may hear this state referred to as "quiescent", which means stable, not changing, and unlikely to change
Cell Cycle
G1- First Growth Phrase G2- follows S phase and features continued cell growth and high metabolic activity, especially the production of microtubules in preparation for mitosis. Go- non-proliferative," meaning they are not actively dividing and may not divide in the future. S- DNA is replicated M- Mitosis
Electrical Synapse
Gap junctions between cells that allow electrical signals to pass very quickly from cell to cell. In HUMANS they are FOUND ONLY in specific locations: the retina, smooth muscle, cardiac muscle, and the CNS.
Nodes of Ranvier
Gaps in the myelin sheath to which voltage-gated sodium channels are confined. There are small gaps between Schwann cells, called the nodes of Ranvier. A signal is able to "Jump" from one node to another without progressing along the entire length of the axon—dramatically increasing transmission speed
The Respiratory SYstem
Gas exchange is the main function Inhalation and expiration for gas exchange and the alveoli. It runs as a high to low concentration, high oxygen flows into low oxygen in the lungs and high CO2 flows out to low CO2 Air pathway= Mouth/nose -> pharynx-> larynx-> trachea-> bronchi-> bronchioles-> alveoli
The Lymphatic System
Gather excess interstitial fluid and return it to the blood; remove from the interstitial spaces proteins and other molecules too big to be taken up by the capillaries; monitor the blood and lymph for infection.
Cofactors
General term for any species required by an enzyme to function Coenzymes and prosthetic groups are both examples of cofactors Cofactors can be permanently bound to the active site or may bind loosely with the substrate during catalysis
Enveloped Viruses
Generally, enveloped viruses acquire their envelopes from plasma membrane when they exit from the cell. Exceptions are herpesviruses, which acquire envelopes from the nuclear membrane.
Mendel's Laws: Law of Independent Assortment
Genes located on different chromosomes assort independently
Sex-Linked Inheritance
Genes located on the sex chromosomes, X and Y, exhibit a unique inheritance pattern. For the MCAT you will only need to understand X-linked inheritance. The easiest way to approach these questions is to use a chromosome Punnett Square. The possible contributions from the father are X or Y, and the possible contributions from the mother are X or X. Place an identifying label on any X that holds the recessive allele. An example is provided below for an affected male crossed with a carrier female.
Germ Cells vs. Somatic Cells
Germ cells are the only cells passed on to offspring (only one of the gametes formed from a germ cell, to be precise). Therefore, ONLY those mutations that occur in germ cells are heritable. Mutations in somatic cells may harm that particular cell during its lifetime, and daughter cells derived from that cell via mitosis, but the next generation will ONLY receive the genetic information found in the sperm or egg cell they receive from each respective parent. Mutations to any or all somatic cells will not be incorporated into the offspring.
PPP: Oxidative Phase
Glucose-6-P → 6-Phosphogluconate → Ribulose-5-P The two steps outlined above are both coupled to the conversion of NADP+ to NADPH NADPH is used to: 1) reduce glutathione disulfide (GSSH) to glutathione (2GSH) 2) act as a cofactor for reductive biosynthesis. For Glucose 6 Phosphate, 2 NADPH molecules NADPH can leads to the production of 4 Glutathiones to protext against reactive Oxygen species
Phenylalanine Tiration and Isoelectric point
Half-equivalence point and buffer region: concentration of NaOH is much lower than phenylalanine; Equivalence point and pI: concentration of NaOH is equal to phenylalanine; End point: concentration of NaOH is much higher than phenylalanine Review titration points and equivalance in CHEM 2
Compact bone
Hard, dense bone tissue that is beneath the outer membrane of a bone the dense bone that surrounds the outside of all bones and constitutes the shafts of long bones. The interiors of flat and irregular bones, as well as the bulbous ends of the long bones, are filled with spongy bone Compact bone is many times more compact. It is organized into orderly units called osteons and the only spaces it contains are Haversian canals, perforating canals, and canaliculi
Hydroxyapatite
Hardy crystals consisting of calcium and phosphate that form the bone matrix. an inorganic compound of calcium, phosphate, and hydroxide. It is the mineral matrix responsible for a bone's strength and is the form in which most all of the body's calcium is stored.
Hemophilia
Hemophilia is more common in males because all X-linked recessive genetic disorders are easier for males to contract. This is seen rather simply by considering that males only need to receive a single "bad X" chromosome to be affected. This is because all males, by definition, will have a Y chromosome rather than a second X chromosome. A Y chromosome does not mask a recessive allele as would another wild-type X. In females, however, two "bad X" chromosomes are required for the female to be affected. As a result, there is no such thing as a male carrier for an X-linked condition. If a male has one copy, he IS affected, and it is impossible for any male to have two copies of an X-linked gene because, by definition, HE only has one X chromosome. When we are not told about the other mate, we always assume that they are NOT a carrier and are NOT affected. If they were, the MCAT would always give this information. This means that the mother in this case must be unaffected, with two normal X chromosomes. Because male children must get the bad X chromosome from their mother (because dad had to give them a Y in order for them to be a male in the first place) NONE of the male offspring will have hemophilia. By contrast, ALL of his daughters must be carriers because the defective X chromosome is the only one he can give to daughters. Note, however, that the daughters will be carriers, but NONE of them will be affected. For a female to be affected with an X-linked recessive condition she must have had an affected father AND a carrier or affected mother.
Lymph Nodes
High concentration of B- and T-lymphocytes. Filters blood for pathogens Bean-shaped filters that cluster along the lymphatic vessels of the body. They function as a cleanser of lymph as wells as a site of T and B cell activation
Starvation
High glucagon and epinephrine levels High rates of gluconeogensis High rate of fatty acid oxidation, for ketone bodies and acidosis
Hydrolyases
Hydrolysis Cleave bonds with the addition of water.
Consumption of ATP: Hydroylsis
Hydrolysis ATP + H₂O → ADP + Pi + energy The inorganic phosphate (Pi) is created rather than a phosphate group being added to another substrate ATP Hydrolysis is normally always coupled to another rxn or process, where that free energy can be used to drive another rxn to work! Think of the cocking of the myosin head we use H2O to get ATP rxn to work
Saponification
Hydrolysis of an ester (triglycerides, phoplipids Triacylglycerols and phopholipids are both esters, AKA THINK OF THE MOTHER FATHERIN STRUCTURE YOU TERD
Mendelian Genetics: Homozygous
If homozygous genotypes are represented by BB (normal) and bb (affected)
Michaelis-Menten Saturation Curve Parallel
Imagine a room with a 50 chocolate vendors milling around in it (enzymes) that will exchange one chocolate bar for a dollar. Buyers (substrates) are slowly allowed to enter the room. At the beginning, it is easy for a buyer to bump into an unoccupied vendor, because there are fewer buyers than vendors. As more and more people enter, though, the room gets crowded, and eventually every vendor is occupied with a buyer. The rate at which the vendors can exchange a chocolate bar for a dollar at this point is Vmax because the vendors have reached a saturating concentration of buyers
Vitamin A
Includes retinol, retinal, retinoic acid, carotenoids It is important for growth and development, and maintence of the immune system and GOOD VISION Vitamin A is needed by the retina of the eye to form retinal, combining protein opsin to form rhodospin, to form a low absorbing molecule FAT SOLUBLE
REVERSIBLE INHIBITION
Inhibitor is not permanently bound, enzyme is not completely disabled Characterized by the ability to replace the inhibitor with a compound of a greater affinity or to remove it using mild lab treatment
Voltage-Gated Sodium Channels
Integral proteins that change shape ("open") in response to a disturbance in the resting potential (i.e., voltage) across the membrane. In their "open" state, they allow the rapid flow of sodium back into the cell. Open during depolarization
Carbohydrate Reaction: Ring Closing
Intramolecular Nucleophilic substitution: OH group on chiral carbon that is furthest from carbonyl carbon acts as a nucleophile It attacks carbonyl carbon (electrophile) Carbonyl oxygen is protonated to form a hydroxyl group
SMooth Muscle
Involuntary, non-striated, one nucleus Controls the gut, viscera, blood vessels, etc Important Feature: --- Not arranged as sarcomeres, and does not do sliding filament mechanism --- It is similar with actin and myosin still sliding past one another, but it's different --- Smooth muscle contraction is initiated by calcium dependent phosphorylation of the myosin head, and the contraction is known as the calcium calmodulin cascade Single unit vs multi-unit ----Unitary, or single-unit, smooth muscle is a group of smooth muscle fibers that are innervated by a single neuron and contract simultaneously as a single group. These are the most common smooth muscle unit and are found in most organs, around most blood vessels, the digestive track, etc. ---A multi-unit smooth muscle is innervated by multiple neurons and does not act as a single unit. This allows for more precise control (remember, however, that all smooth muscle is involuntary, so it is not conscious control). Multi-unit smooth muscle is quite rare. It is found in some of the larger vessels such as the aorta, and in the retina of the eye.
The Pancreas
It is both an endocrine and exocrine gland - Exocrine due to the digestive enzymes that is secreted into an "external" opening - Endocrine due to secretion of insulin and glucagon INTO the blood Secretes biocarbonate rich solution, which neutralizes the stomach acid, decreases acidity of the intestine to pH= 6 Secretes trypsin, chymotrypsin, pancreatic amylase, lipase, ribonuclease, deoxyribonuclease ALL pancreatic secretions empty into the upper end of the duodenum, just before empyting into the duodenum, the pancreatic duct is joined by the bile duct.
Glycolysis
KNow what enters and exits the cycle, where they came from and where they go next. Remember it occurs in the cytoplasm Know the substrate and the final product of each step, you don't need to know the enzyme names Be familiar where ATP is required or produces and where NAD+ is required and NADH is produced KNow the precise number of high energy molecules required and the NET number of high energy molecules produces, per glucose ( NADH/ NAD+, ATP/ADP) ---Glycolysis produces 2 ATP, 2 NADH, and 2 pyruvate molecules
Q. 28 Fructose and electron flow
Ketone
Transamination
Key step in protein metabolism for energy Exchange of an imne group one moelcule for a carbonyl on another For example, transamination of Glu forms alpha-ketoglutarate, an intermediate in the Citric Acid Cycle
Michaelis Constant
Km= Relative measure of an enzyme's affinity for it's substrate The magnitude of Km is inversely proportional to substrate-enzyme binding affinity The lower the Km the stronger the binding affinity ---As Km decreases, binding infinity increases ---As Km increases, binding affinity decreases Km= [S] @ 1/2Vmax ALWAYS, remember this
Keto-Enol Tautomerism of Monosaccharides
LIke other Ketones and Aldehydes, sugars can alternate between keto and enol
Cell Body
Largest part of a typical neuron; contains the nucleus and much of the cytoplasm
Spongy Bone
Layer of bone tissue that has many small spaces and is found just inside the layer of compact bone. Spongy bone contains many open spaces, formed by the interwoven trabeculae. These spaces are filled with red bone marrow. Compact bone is many times more compact. It is organized into orderly units called osteons and the only spaces it contains are Haversian canals, perforating canals, and canaliculi
non-Mendelian inheritance patterns: Limited Expressivity
Limited Expressivity is the case in which various individuals all have the same genotype AND all of them have the disease phenotype (i.e., 100% penetrance), but individuals are impacted in varying degrees Think of Mitchell, Justin, and Kanu
Smooth ER (SER)
Lipid synthesis/modification Lipids are made at the ER, but metabolized in the mitochondria
Intracellular Receptors
Lipid-soluble hormones (e.g., steroids) do not require a plasma membrane surface receptor. They dissolve through the membrane and bind targets in the cytosol. In most cases, their activated target then acts inside the nucleus on the promoter region of a gene. 2 Angiotensin is an example of intracellular receptor and hormone relationship Intracellular receptors are receptors located inside the cell rather than on its cell membrane. Classic hormones that use intracellular receptors include thyroid and steroid hormones
Tissue- Specific Metabolism
Liver= Glucose in well fed state, fatty acids during fasting, but NO KETONES Muscle= Differs by muscle type and duration of use --- Cardiac= fatty acids in well fed state, but fatty acids And ketones in fasting state --- Skeletal= Glucose during well fed state, FATTY ACIDS AND KETONES if fasting Exercise duration is also a factor, the main fuel is glucose form glycogen, then switches to lactic acid fermentation during prolonged exercise. If exercise continues longer, muscles will use fatty acids Brain= GLucose in well fed state and fasting states. Ketones in prolonged fast or starvation Adipose tissue= Glucose in well fed state, fatty acids during fasting RBC= Glucose in all states ALWAYS ANAEROBIC GLYCOLYSIS, meaning always going through anaerobic fermentation
Thymus
Location where T-lymphocytes (a.k.a. T cells) acquire immunocompetency, differentiate, and mature. An immune organ located near the heart. The thymus is the site of T cell maturation and is larger in children and adolescents. Secretes thymopoietins & thymosins. These along with THF & TF are involved with normal T cell (lymphocytes) development.
Bone Types
Long bones (e.g., femur, humerus) Short bones (e.g., tarsals, carpals) Flat bones (e.g., skull, sternum), Irregular bones (e.g., hip, vertebrae)
Vas Deferens
Long, narrow tube carrying sperm from epididymis to ejaculatory duct a duct that connects each testicle with the urethra. Beginning at the epididymis, it leads up the inside of the scrotum, into the pelvic cavity, past the seminal vesicles, through the prostate gland, and empties into the urethra before the urethra enters the penis.
Lymph Nodes
Lymph nodes are filled with lymphocytes. These immune system cells monitor the blood for foreign antigens and fight infections
Lymphatic Vessels
Lymphatic vessels, also known as lymphangions, are a lot like veins in that many of them (but not all) contain one-way valves. Backward flow is restricted when single cells overlap slightly, creating a trap door that allows fluid in, but not back out. The entire lymph system eventually drains into two main vessels, the right lymphatic duct and the thoracic duct, which both dump back into the blood stream by merging with large veins in the lower portion of the neck.
Macrophage Antigen Presentation
Macrophages engulf microbes and present antigens from those microbes on MHC proteins in their cell membranes to be recognized by B-cells and T-cells
The Excretory System (The Kidneys)
Main Functions are to excrete liquid and solute waste such as excess water, salts, nitrogenous wastes. It also has a role in maintaining pH (bicarbonate system), osmolarity and blood pressure
Mucous Neck Cells
Make and secrete mucus into gastric pits, which lead to the stomach lumen PROTECT AGAINST ACIDITY The secreted mucus is alkaline, provides protection from corrosion due to extreme acidity of the stomach remember: goblet cells are mucus-secreting cells found in the linings of the intestines and respiratory tract, NOT mucus cells
Chief Cells
Make and secrete zymogen pepsinogen into gastric pits/stomach lumen Acid is the other molecule that assists in protein metabolism to denature the protein
G-Cells
Makes and Secrete Gastrinc Gastrin is released into the blood (NOT INTO GASTRIC PITS/STOMACH LUMEN) It circulates to the parietal and chief cells to stimulate HCl and pepsinogen release, to further enhance digestion
Metaphase
Metaphase is indicated by the chromosomes lining up at the metaphase plate and formation of the spindle apparatus.
Cilia
Microtubules similar protrusions found on the lumen-facing side of many epithelial cells lining various cavities in the body The cell is fixed in place and the cilia create a beating pattern that moves fluid and or other extracellular materials past the cell Examples: -the ependymal cells that line the ventricles of the brain and the hollow center of the spinal cord (move cerebrospinal fluid), -the epithelial cells that line the respiratory track (move mucus and debris), -the cells that line the fallopian tubes (move the egg toward the uterus). Eukaryotic cilia and flagella exhibit the 9+2 arrangement of microtubules while prokaryotic flagella are polymers of the protein flagellin. In humans, cilia are found exclusively in the: Respiratory System (lungs) Nervous System (ependymal cells) Reproductive System (uterine tubes)
Flagella
Microtubules whip-like projections from the cell body used for locomotion In humans, sperm cells are the only cells that have flagella Eukaryotic cilia and flagella exhibit the 9+2 arrangement of microtubules while prokaryotic flagella are polymers of the protein flagellin.
Agranulocytes
Monocytes that become macrophages and lympcytes These cells live for months to years.
Macrophages
Monocytes, a type of white blood cell, mature into macrophages, which phagocytize pathogens and cellular debris. Phagocytosis by macrophages is non-specific and a type of innate immunity, but macrophages also present antigens from pathogens they consume for recognition by B and T cells, an aspect of acquired immunity
Polymerization
Monosaccharide-> Disaccharide-> Polysaccharides Alpha-Linkage= linked through an oxygen that is on the opposite side of the plane form CH2OH group (trans) Beta Linkage - LInked through an oxygen that is on the same side of the plane as CH2OH group (CIS)
non-Mendelian inheritance patterns: Mosaicism
Mosaicism is the case in which different cells within the same individual contain non-identical genotypes (NOT different alleles for the same gene, but different genotypes. Normally, all cells have the same genotype: Tt, Rr, etc. In this case one cell line may be TT and the other Tt).
Fungi
Mushrooms, yeasts and molds o All fungi are heterotrophs. Most are saprophytic (live off of dead, decaying matter), but a few are parasitic (live off of live host, often killing it), or mutualistic (symbiotic relationship with living host, as in mycorrhizae—a symbiosis between fungi and plant roots). Fungi cells walls are made of chitin
Symbiosis: Mutualism
Mutualism is a form of symbiosis where both participants benefit equally
Thick filament
Myosin Motor protein Myosin subunits form myosin fibers, a globular head and tail Two of these fibers intertwine to make up a myosin molecule, a dimer Many myosin molecules form the long myosin filaments of the sarcomere The heads protrude from the myosin from the moyosin filament at an angle in the relaxed conformation, referred to as bent in the sliding filament model Myosin heads like actin and binds to it unless it is stopped by tropomyosin when contracting, some myosin heads must release while others simultaneously bind to allow the myosin to "crawl" along the actin filament
Bacteria Reproduce through Binary Fission
NO mitosis or meiosis; distribution of extrachromosomal DNA (i.e., plasmids) is random and daughter cells may or may not receive a copy; bacteria have three ways of increasing their genetic variability through conjugation, transformation, transduction
ACTH
Name: ACTH Peptide/Water soluble Function: stimulates adrenal cortex for glucocorticoids, stress hormones Organ that secretes it: Anterior Pituitary Where the endocrine organ is located: Brain
ADH (endocrine)
Name: ADH Peptide/Water soluble Function: Cause collecting duct of kidney to become permeable to water, concentrating urine Organ that secretes it: Posterior Pituitary Where the endocrine organ is located: Brain
Calcitonin
Name: Calcitonin Peptide/Water soluble Function: A polypeptide hormone especially from the thyroid gland that tends to lower the level of calcium in the blood plasma. Organ that secretes it: Thyroid Where the endocrine organ is located: Throat
TSH
Name: TSH Peptide/Water soluble Function: Stimulates release of T3 and T4 from thyroid Organ that secretes it: Anterior Pituitary Where the endocrine organ is located:
Seminiferous Tubules
Narrow, coiled tubules that produce sperm in the testes.
Evolution & Populations: Natural Selection
Natural selection is the more precise term for the concept described by "Survival of the fittest. the process by which individuals with genetic traits that provide them with a fitness advantage produce more offspring, and therefore those advantageous traits become more prevalent in subsequent generations
Northern Blot
Nearly identical to a Southern Blot; used on RNA instead of DNA.
Feedback Inhibition
Negative Feedback A specific type of non-competitive or allosteric inhibition that applies to multi-step reactions, synthetic pathways, or cascades. One of the products of a reaction later in the chain acts as an inhibitor for one of the enzymes earlier in the chain. A method of metabolic control in which the end product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway. It is essentially telling the pathway we don't need anymore of this substance.
Simple Diffusion
Net movement of dissolved particles from higher concentration to a region of lower concentration No ATP required
Reaction Rate vs Substrate Concentration
No Inhibitor A competitive Inhibitor Noncompetitive Inhibitor Irreversible Inhibitor Talk about the graph and why each inhibitor as represented the way it is.
Coenzymes
Non -protein species NOT permanently attached to the enzyme, but required by the enzyme to function An organic molecule that is a necessary participant in some enzymatic reactions; helps catalysis by donating or accepting electrons or functional groups; e.g., a vitamin, ATP, NAD+. example is thiamine pyrophosphate (TPP), which is tightly bound in transketolase or pyruvate decarboxylase, while it is less tightly bound in pyruvate dehydrogenase. Other coenzymes, flavin adenine dinucleotide (FAD), biotin, and lipoamide, for instance, are covalently bound.
Oxidation Process for Unsaturated Fatty Acids
Normal Beta Oxidation creates a double bond in 2-3 position, but if a double bond is there, beta oxidation cannot proceed Enoyl-CoA isomerase causes themovement of double bonds to the 2-3 position for oxidation to occur again Conjugated double bonds also stop beta oxidation, thus enzymes delete one of the two double bonds and Enoyl-CoA isomerase moves the double bond to the 2-3 position
Post-Translational Modification
Occurs at the endoplasmic reticulum and the Golgi apparatus; usually includes addition of polysaccharides, lipids, or phosphates
Lipid Metabolism: Beta-Oxidation of Fatty Acids
Occurs in the mitochondrial matrix with the exception of extra long chain fatty acids enter frist via peroxisome to be broken down to smaller pieces than can be oxidized in the mitochondria Fatty acids enter inner mitochondrial membrane via carnitine shuttle Carbons re removed two at a time to form Acetyl-CoA that then goes to the CAA ---Beta Oxidation requires the following per 2 carbon cycle: 1 FAD, 1H2O, 1 NAD+, 1 CoA-SH Net Results per 2 carbon cycle= 1 FADH2, 1 NADH, 1 Acetyl-CoA Remember, FADH2= 2 ATP, 1 NADH= 3ATP, 1 Ace. CoA =12 ATP To know how many cycles a fatty acid will go through, simply divide the number of carbons by 2 and subtract 1. --- 14 carbon= 7-1= 6 cycles For odd # chain, -1 then divide by 2 and -1 again ---- Example- 17 chain= 17-1=16, 16/2=8, 8-1= 7 cycles ---- Odd number results in 3 C residue, propionyl CoA is left over and forms Succinyl-CoA and goes back to Krebs. Don't memorize names, just know there is leftover stuff
Tissue Organization
Organ Systems > Organs > Tissues > Cells
Facilitated Diffusion
Osmosis: Diffusion of water across a semi-permeable Membrane No ATP required A process in which substances are transported across a plasma membrane with the concentration gradient with the aid of carrier (transport) proteins; does not require the use of energy. An example of this is the sodium and potassium CHANNELS
ATP Synthase
Oxidative Phosphorylation occurs here The ETC itself isn't Oxidative phsoporylation, only where the ATP synthase is the oxidative phosporylation. It's the phosportylation of the ADP and the Pi combining, with the O2 being the final e- acceptor Chemiosmotic Coupling= Direct Coupling of eneryg inherent in the electrochemical gradietn across the inner mitochondrial membrane for phosporylation of ADP to ATP --- When a drug uncouples ETC or the E.C. gradient form oxidative phosphorylation, it means the H+ gradient no longer drives ATP production in ATP synthase. --- THe proton motive force that occurs from protons, H+, moving down their electrochemical gradient from the ETC, produces ATP. They move DOWN their CONCENTRATION GRADIENT and ELECTRICAL GRADIENT.
Formation of ATP: Oxidative Phosporylation
Oxidative Phosphorylation- FOrmation of ATP out of ADP and a free organic Phosphate through a proton gradient in the inner mitochondrial membrane. This gradient is created as a result of the oxidation of high energy molecules of NADH and FADH2 to pump out protons We are oxidizing electron carriers to generate ATP OXIDATIVE PHOSPORYLATION USUALLY OCCURS AT ETC, to push together ADP + Pi to form ATP Occurs in the mitochondria matrix and done through the ATP synthase complex
Pentose Phosphate Pathway
PPP = Keep it simple 1) NADPH synthesis 2) Ribose-5-Phosphate (R5-P). NADPH- reducing agent, reductive biosynthesis for synthesizing fatty aicds and sterols, and is necessary for production of Glutathione, an antioxidant against peroxide and radical byproducts R5-P- Synthesize nucleotides, it is oxygen bearing ring for all nucleotides, is used to synthesize nucleotides. It is the oxygen-bearing ring of all nucleotides, including the famous deoxy-ribo-nucleic acid. 2 Phases- Oxidative and non-oxidative phase occurs in the cytoplasm of most cells, generating NADPH and sugars for biosynthesis
Symbiosis: Parasitism
Parasitism is a symbiosis wherein one participant benefits at the expense of the other (i.e., the other participant is harmed ticks, mosquitoes, blood suckers, etc
Molecular Cloning: Phage
Phage is an abbreviated name for a bacteriophage (a virus that infects bacteria). As an alternative to the use of a bacterial plasmid as just described, the vector can also be inserted into a bacteriophage. Bacteria are then infected with the phage. The phages take over the machinery of the bacteria they infect in order to reproduce large numbers of new phages. This also results in many copies being made of the vector and the target sequence that was inserted into it
Mendelian Genetics: Phenotype
Phenotype refers to the expression of the gene in terms of its visible or observable characteristics
non-Mendelian inheritance patterns: Pleiotropy
Pleiotropy describes the situation in which one single gene contributes to multiple phenotypic traits
Isoelectric Point
Point at which a compound is electrically neutral, so the molecule is usually in the form of a zwitterion. The isoelectric point is most similar to the equivalence point in acid-base titration. In acid-base titration, the equivalence point is the point at which all of the starting solute is neutralized by the titrant. At that point the acid and the base are present in equal quantities. This is similar to the isoelectric point, because in both cases the acid and the base are both neutralized at that specific pH, rendering a net charge of zero. the pH at which a molecule carries no net charge. For molecules that have two pKas, the equation for pI is: pI = (pKa1 + pKa2)/2. At a pH higher than the pI, the molecule will have a net negative charge. in solution: WHEN pH < pKa, the amino acid is protonated WHEN pH> pKa, the amino acid is deprotonated
Hydrolysis of GLycoside LInkage
Polymer (n) + H2O -> Polymer (n-1) + monomer
DNA
Polymer of Deoxyribose Nucleotides
Evolution & Populations: Polymorphisms
Polymorphisms are random variations in genetic sequence among individuals. Polymorphisms are random, usually due to mutation, and may or may not be increasingly represented in future generations depending on whether or not that particular genetic variation provides an evolutionary fitness advantage
Fasting State
Postabsoprtive High glucal levels to get glucose back into the blood, thus there are low insulin levels are low cause we aren't storing the goods High rates of catabolism than anabolism Glycogenolysis causes increase immedietaley Gluconeogensis is a delayed increase
Well-Fed State
Postprandial, Absorptive- FIRST FEW HORUS AFTER EATING A MEAL High insulin levels to store the goods Low glucagon levels High relative rate of anabolism vs catabolism Higher rates of glycogen and fatty acid synthesis occurs during this state.
Adenosine Triphosphate (ATP)
Primary Energy currency for the Human body ΔG°' for ATP Hydroylsis << 0 Losing one phosphtate group changes ATP-> ADP-> AMP --- Through cyclization, AMP -> cAMP --- Remember, cAMP us the most common 2nd messenger molecule on the MCAT ---- All these transitions have a - ΔG°', they are exergonic ---- Only AMP-> cAMP is endergonic, and is higher energy than ATP These phospoanhydride bonds that connect the Pi groups are effective energy storages for the cell, they are highly energetic. There is alot of repulsion between the Pi groups. As it decreases from ATP to other forms, it goes to more stable energy states, thus why ΔG° is negative.
Fructose Metabolism
Primary sugar in many fruits; also a product of sucrose hydrolysis @ MUSCLE & KIDNEYS: Hexokinase converts Fructose -> Fructose-6P (F-6P is then funneled into the 3rd step of GLY)
Memory B cells
Produced during a B cell response, but are not involved in antibody producing during the initial infection; are held in reserve for the rest of your life in case you encounter that pathogen again. memory B cells that remain in the body, allowing the immune system to mount a more efficient secondary immune response if there is a later infection by the same pathogen
Bulbourethral Gland
Produces preejaculatory fluid secrete alkaline substance (clear, sticky fluid), often secreted before ejaculation to prepare urethra for sperm
The Immune System
Protect the body from infection and disease Destroy pathogens invading the body Macrophages, neutrophils, basophils, eosinophils, mast cells, dendritic cells, natural killer cells, t-cells, b-cells, plasma cells, memory b cells, helper T cells, suppressor T-cells, killer t-cells, memory t-cells
The Integumentary System
Protection against abrasion, physical barrier to pathogens, vitamin D synthesis, insulation/cushioning (due to subcutaneous fat), prevention of water-loss, temperature regulation o Includes the hair, nails, skin, and the oil and sweat glands located within the skin
Purines and Pyrimidines
Purines-Guanine, Adenine Pyrimidines- Cytosine, Thymine
Lactic Acid Fermentation
Pyruvate → lactate (Uses lactate dehydrogenase) lactate is produced and is the final electron acceptor.
RNA vs DNA
RNA has a 2' hydroxyl group; DNA does NOT RNA is normally single-stranded; DNA is normally double-stranded RNA contains uracil bases; DNA contains thymine bases RNA exits the nucleus into the cytoplasm; DNA always stays in the nucleus
Transcription
RNA polymerase binds to the promoter region with the aid of various transcription factors. Helicase unwinds the DNA, forming the transcription bubble. RNA polymerase reads the template strand in the 3' to 5' direction, creating a pre-mRNA transcript that matches the coding strand with U substituted for T. Termination factors cause the release of the mRNA transcript. During post-transcriptional processing, large sections of non-coding sequences called introns are spliced out, leaving only the exons, or sequences that code for actual amino acids in the eventual protein. A poly-adenosine tail (a.k.a., "poly-A tail") is added to the 3' end, along with a 5' cap. This is the mature mRNA strand that will be translated at a ribosome. Be extremely careful with the terminology used in reference to transcription. There are five terms you must clearly differentiate: "Template Strand," "Anti-Coding Strand," and "Anti-Sense Strand," all refer to the strand of DNA that is transcribed. "Coding Strand," and "Sense Strand," both refer to the strand that is NOT transcribed. Always remember that a transcription is NOT an exact copy. It is complementary and substitutes U for T. It also uses a different sugar, ribose, instead of deoxyribose
Isomerases
Rearrangments Phospglucose isomerase (G6P -> F6P), epierases catalyze the rearrangement of bonds within a molecule
Afferent Neurons (Sensory)
Receive sensory signals from sensory cells.
Oxidoreductases
Redox reactions Oxidorecuctases can be oxidases or dehydrogenases. an enzyme that catalyzes the transfer of electrons from one molecule, the reductant, also called the electron donor, to another, the oxidant, also called the electron acceptor
Bacteria
Remember that all bacteria are prokaryotes and A prokaryote is a unicellular organism that lacks a membrane-bound nucleus, mitochondria, or any other membrane-bound organelle Basic structure: -Capsule, -peptidoglycan cell wall -plasma membrane -no complex membran -bound organelles -single circular DNA chromosome, -tiny circular DNA molecules called plasmids.
centriole
Responsible for division of the cytoplasm in animal cells; they are not present in plant cells. They consist of 9 triplets of microtubules arranged in a circle. Aid in cellular division
PPP- NOn-Oxidative Phase
Ribulose-5-Phosphate → R5-P ↔ SUGAR POOL ↔ Glucose-6-Phosphate Sugar pool- carbs that are not needed to be known R5-P is funneled into nucleotide synthesis KNOW THIS: 1) Conversion into the SUGAR POOL from Ribulose-5-Phosphate, interconversions between sugars within the pool, and conversion to Glucose-6-P are all catalyzed by either Transketolase or Transaldolase. 2) All of the reactions into, out of, and inside of the pool are reversible.
The Genetic Code: know the start codon and the 3 stop codons
START: AUG STOP: UAA, UAG, UGA Mitochondria do NOT use the same genetic code to translate their own DNA The human genetic code is said to be both degenerative and unambiguous. What does this mean? -The code is said to be degenerative because given a specific amino acid it cannot be determined which codon coded for that amino acid—it could have been multiple codes, usually at least two or three. This redundancy is considered degenerative because you cannot know the codon from the amino acid. The code is considered unambiguous because given a codon, there is no ambiguity about which amino acid it will code for. Even though multiple codons may code for the same amino acid, none of those individual codons will ever code for a different amino acid
Eryhtrocytes
Sacks of hemoglobin; immature RBCs start out with a nucleus and organelles, but mature RBCs have no organelles.
Autonomic
Sensory: Voluntary; innervates skeletal muscle; contains both sensory and motor subdivisions. Motor: The motor subdivision of the autonomic nervous system contains the "sympathetic" and "parasympathetic" divisions
Eastern Blot
Similar to a Western blot, but used to verify post-translational modification. The probes used bind to lipids, carbohydrates and phosphates (i.e., the most common posttranslational modifications).
Terminal Button
Small knobs at the end of axons that secrete chemicals called neurotransmitters a projection at the end of the axon that synapses with the dendrite of another neuron or with the effector There are a Ca+ channel, and when action potential hits this point, it causes Calcium to flow in.
Spleen
Somewhat analogous to a lymph node that filters blood instead of lymph; high concentration of leukocytes (WBCs) and platelets; storage of a considerable amount of blood that can help combat hemorrhagic shock; breaks down and recycles parts of old erythrocytes (RBCs).
Evolution & Populations: Speciation
Speciation simply means the formation of new species from existing ones
Acquired Immunity
Specific response to one particular virus, bateria, or specific pathogen based upon prior exposure 2 types: humoral and cell mediated
Causes of DNA Damage
Spontaneous Hydrolysis: DNA reacts in solution without external stimuli or chemicals. For example, amine groups on DNA bases can react with water to form a carbonyl; via hydrolysis the entire DNA base can be replaced by a hydroxyl group. Damage by External Chemicals or Radiation: When exposed to radiation, neighboring pyrimidines react with each other to form a covalent dimer; various chemicals cause alkylation of functional groups on the DNA base; carcinogens are often large polycyclic compounds that bind to the DNA and create bulky side groups. Mismatched Base Pairs: Results from errors during replication or methylation of guanine (a specific form of methylated guanine pairs with thymine instead of cytosine)
Gram Negative
Stain pink Relatively thin cell wall Do NOT form endospores Contain two (2) cell membranes: one inside the cell wall and one outside the cell wall.
Gram Positive
Stain purple Very thick cell wall Form endospores Single cell membrane
Aldosterone (Endocrine)
Steroid Function: - Increase sodium reabsorption and potassium secretion at distal convoluted tubule and collecting duct - Net increase in salts in plasma -Increase osmotic potential and blood pressure Organ that secretes it: Adrenal Cortex
Cortisol
Steroid Function: Stress hormone, increases gluconeogensis in liver and increases blood glucose levels, stimulates fat breakdown Organ that secretes it: Adrenal COrtex
Adherens Junctions
Strong Mechanical Attachments Uses cadherins or integrins. Links to actin filaments to alter shape of cell or tissue found in epithelium and between cardiac muscle cells
Formation of ATP: Substrate Level Phosphorylation
Substrate Level Phosphorylation- Formation of ATP from ADP occurs through an exergonic rxn in the cytosol, as part of glycolysis and ALSO in the matrix of the Mitcochondria when GTP is formed in CA cycle GLYCOLYSIS AND KREBS CYCLE... Usually done with Kinases, and does it on a substrate level, you know when a phosphate is donated to a molecule. This is called substrate-level phosphorylation
Brush border
Surface of a cell covered with microvilli. increases surface area of a cell for absorption The brush border is a name given to the microvilli and the collection of mucus and digestive enzymes intermingled within them. The name was chosen because under a light microscope individual microvilli are not easily discernible and they appear instead as a fuzzy line along the apical surface of the epithelial cells.
Evolution & Populations: Survival of the Fittest
Survival of the fittest is a term meaning that the individual best suited to its environment will be most likely to survive and pass on its genetic information to future generations
Symbiosis: Lichen
Symbiosis between fungi and algae
Symbiosis: Mycorrhizae
Symbiosis between fungi and plant roots
Helper T-Cells
T-cells that "help" other immune system cells, such as B-cells and cytotoxic T-cells, to perform their function. The way they "help" other cells is usually to secrete chemicals, such as cytokines, that activate (i.e., "turn-on") functions or activities in the cell that is being "helped"
Telomeres
Telomeres are long sections of repetitive DNA nucleotides found at both ends of each chromosome. THey protect the DNA from potential dna damage... it is what is actually being shortened in the DNA during replication They provide a buffer region of non-coding DNA so that these repetitive losses in length do not affect a gene sequence. Approximately 50 replication cycles will consume the entire telomere region and any subsequent replications will result in the loss of gene sequences
Telophase
Telophase is indicated by the nuclear membranes beginning to re-form and the chromosomes unwinding. Many diagrams will also show the beginning of cytokinesis. Some diagrams will also show a single cell with a well-defined nuclear membrane and uncoiled chromosomes. This would indicate interphase
Denaturing Proteins
Temperature- Denatures 2nd, 3rd, and 4th protein structures, but not 1st pH- Can disrupt ionic bonds in the 3rd and 4th structures Chemicals- breaks Hydrogen bonds, breaking 2nd, 3rd, and 4th protein structures Enzymes- Alter protein primary structure. Protein Denaturing Agents: -acid, ehat, urea, mercaptoethanol
A and I band, H zone, Z and M lines
The A band is the length of the myosin filaments and does NOT change during contraction. The I band is the distance between the ends of the myosin filaments in one sarcomere to the ends in the next sarcomere. It is also the lightest band when viewed under a microscope because only the thin actin filaments are present in this region. The I band will shorten during a contraction. The H zone is the distance between the ends of the actin filaments. The H zone will also shorten during a contraction. The Z lines (a.k.a. Z discs) appear as zigzag lines that define the edges of each individual sarcomere unit. The actin filaments are anchored here by the protein connection and stretch out in both directions. During a contraction the distance between Z lines decreases as the sarcomere shortens. The M line is the center of the myosin filaments. The distance between M lines between two sarcomeres will decrease during a contraction.
Template Strand
The DNA strand that provides the template for ordering the sequence of nucleotides in an mRNA transcript. Anti-coding strand, anti-sense strand, and template are the same things
Anti-Sense Strand
The DNA strand that serves as the template for synthesis of mRNA. It is complementary to the sense strand.
Sense strand
The DNA strand which is always represented on paper. The strand is always the one running from the 5' to the 3'. mRNA is identical to the strand except Thymine is replaced with Uracil.
The strand of DNA that is NOT transcribed will be an exact match to the pre-mRNA formed with one important exception:
The coding strand is identical to the pre-mRNA except for U is substituted for T
R Groups Determine Chemistry
The combination of the R groups in a protein EXCLUSIVELY DETERMINES it's chemistry and folding pattern Will a substrate bind in an active site? -- Depends on existence of completementary charges on the R groups or the hydrophilicty or hydrophobicity of the R groups How will a protein fold? -- Hydrophobic R groups fold INTO the protein core (hydrophobic environment -- Hydrophilic R Groups- More common on surface of protein (Hydrophilic environment) ---Proteins with low hydrophobicity do not fold in a stable structure, but can retain function Reaction mechanisms in the enzyme pocket? -- All depends on chemistry of the R groups -- You can predict the amino acid present in protein ligand or enzyme active site by knowing how the protein is functioning SO WHENEVER YOU SEE PROTEIN OR ENZYME THINK: What amino acids are present and what is the chemistry of the R Groups?
Descending loop of Henle
The descending Loop of Henle travels into the very hypertonic medulla. This section of the nephron is impermeable to salts, but very permeable to water. Water therefore flows out of the filtrate and into the medulla, concentrating the urine. Descending loop = Diffusion of water
Electrical System of the Heart
The electrical signal originates at the SA node, then spreads across both atria to the AV node. There is a slight delay, then the signal travels from the AV node down the bundle of His and through the Purkinje fibers. At the end of the Purkinje fibers the signal travels cell to cell through gap junctions.
The Endocrine System
The endocrine glands and exocrine glands are all within this system. Exocrine glands will release enzymes or liquids to EXTERNAL environment. Examples of this are in the digestive tract, epithelial lined orifices, sweat, oil, mucus, digestive enzmes Endocrine lgands release hormones into INTERNAL FLUIDS OF THE BODY SUCH AS BLOOD, LYMPHS
Meiosis I
The first division of a two-stage process of cell division in sexually reproducing organisms that results in cells with half the chromosome number of the original cell. Meiosis I takes a cell with 23 pairs of homologous chromosomes, or 46 total chromosomes, and creates two cells, each with 23 non-paired, non-homologous chromosomes. Recombination/crossing over occurs in prophase 1 and before metaphase of meiosis Synapsis occurs in prophase 1, it is the interwining of chromosomes that allows for cross over, thus increasing genetic diversity You should also know that chromosomes generally decrease in size, with chromosome One being by far the largest
Prophase II
The first phase of meiosis II. Prophase II is identical to mitotic prophase, except that the number of chromosomes was reduced by half during meiosis I.
Telophase II
The fourth and final phase of meiosis II. Telophase II is identical to mitotic telophase, except that the number of chromosomes was reduced by half during meiosis. I.
Mendelian Genetics: Genotype
The genotype refers to the specific alleles held by that individual. Note that individuals with different genotypes (TT and Tt) can exhibit the same phenotype (tall and tall).
Glomerulus
The glomerulus is a fenestrated capillary bed that strains the blood—allowing fluids, ions, and molecules the approximate size of glucose or smaller to pass through into Bowman's capsule. Blood cells and larger blood components remain within the capillaries and exit via the efferent arteriole which eventually empties into the renal vein.
The Liver
The liver is the mtabolic brain of the human body. It regulates the blood concentration of mayn solutes, key roles in metabolism, detoxifies chemicals, recycles metabolites, makes biomolecules main key functions: -Produce bile (stored in gall bladder) - Filters blood to remove toxins, drugs, metabolites, bacteria - Produce blood plasma proteins like albumin, prothrombin, fibrinogen -Regulates amino acid levels in the blood - Produce cholesterol and lipoproteins and packages for transport (LDL, (HDL)
Relative Refractory Period
The period of time following an action potential when it is possible, but difficult, for the neuron to fire a second action potential due to the fact that membrane is further from theshold potential (hyperpolarized). During this time, a second action potential can be initiated, but a stronger-than-normal stimulus will be required. This makes sense because the firing of an action potential is an all-or-nothing event dependent on the polarity of the membrane reaching the threshold potential.
Mendelian Genetics: Mendelian Ratio
The ratio of occurrence of various phenotypes in any cross involving Mendelian characters; especially : the 3:1 ratio shown by the second filial generation of offspring from parents differing in respect to a single character
Metaphase II
The second phase of meiosis II. Metaphase II is identical to mitotic metaphase, except that the number of chromosomes was reduced by half during meiosis I.
Somatic
The sensory subdivision of the autonomic nervous system is not well developed, explaining why visceral pain is often referred (i.e., felt at a location other than the actual source) and poorly localized.
Molecular Cloning: Recognition Sequence
The specific base sequence recognized by the endonuclease the endonuclease ONLY cuts at one sequence, any fragment cut by that same enzyme will be complementary to any other fragment
Origin of Replication
The specific location on a DNa strand where replication begins.. Prokaryotes typically have a single origin of replication, while eukaryotes have several per chromosome. Is the location on the chromosome where replication begins. For human chromosomes there are multiple origins
Carbohydrate Metabolism
The sum of all chemical reactions in the body Respiration- The breakdown of macromolecules into smaller species to make ATP, when a organic compoudn serves as the electron acceptor in order to generate ATP: --- Aerobic-involves the use of oxygen for the final electron acceptor --- Anaerobic- does not involve oxygen, uses another molecule for the final electron acceptor, usually refers to fermentation, usually done in muscles for humans, and bacteria and yeast use this type of respiration Obligate aerobe vs Faculatative Aerobe: -The term "obligate" implies that there is no other option, so obligate aerobes must use aerobic respiration and cannot survive without oxygen, while obligate anaerobes must use anaerobic respiration and cannot survive in the presence of oxygen. -"Facultative" implies that the organism will use whichever respiration is available. So if oxygen is present, the organism will use aerobic respiration, and if oxygen is absent, the organism will use anaerobic respiration. Facultative anaerobes prefer anaerobic conditions while facultative aerobes prefer aerobic.
non-Mendelian inheritance patterns: Polygenic
The term polygenic is used when many genes contribute to one phenotypic trait.
Dendritic Cells Antigen Presentation
These cells are antigen presentation experts. They are specialized to perform this function efficiently and are found in highest concentration near membranes (such as the skin) that interface with the external environment
Neural Support Cells:
These cells are not neurons that conduct electrical potentials, but cells in the nervous system that provide support to neurons. Schwann cells (oligodendrocytes in the CNS), cells lining the cerebrospinal fluid cavities (ependymal cells) and structural support cells (astrocytes) are a few prominent examples.
PDH Complex
Think f of PDH as the link between glycoylsis and CAC These 3 Enzymes is what converts pyruvate to acetyl-CoA, for the CAC Pyruvate = 3 Destinations: PDH Complex → Acetyl-CoA Lactate Dehydrogenase → Lactate Pyruvate Carboxylase → Oxaloacetate
CO2 + H2O <-> HCO3- + H+
Think of Physiology and how the body seeks to stay at equilibrium. WHen there is an Increase in H+, the hemoglobin will make more CO2 in order for it to be exhaled. More CO2 will shift to the right, causing more bicarbonate to be made and the kidneys to deal with this change. The lungs and the kidney are working together to keep the pH balanced CO2 + H2O ↔ H2CO3 H2CO3 ↔ HCO3- + H+ Carbonic Anhydrase
Consumption of ATP: Phosphorylation using ATP
This is is a major human body regulatory mechanism Many enzymes, proteins, and signaling molecules are turned on and off via phosphoryl group transfers ATP will act as a donor of the Phosphate group for phosporylation Protein Kinases, enzymes, catalyze phosporylation coupled to ATP cleavage Remember that phosphorylation is different from dephosphorylation due to phosphorylation using protein kinases and ATP dephosphorylation using phosphates and produces free Pi Glycogen Phosporylase-A (GPA), enzyme that catalyzes glycogen to glucose GPA# + 2ATP -> GPA-PP** + 2ADP #- Inactive **- Active
Blood
Transport nutrients, gases, waste products and hormones to and from cells; regulate the extracellular environment; help maintain homeostasis; repair injuries; protect the body from foreign bodies (i.e., antigens). It is made up of WBC aka leukocytes, rbc or eryhtrocytes, antibodies/ immunoglobulins, clotting factors, transport proteins, paltelets It is connective tissue
Southern Blot
Used to verify the presence/absence of a specific DNA sequence. It will also indicate the relative size of restriction fragments
Skeletal Muscle
VOLUNTARY, STRIATED, MULTINUCLEATE Tendons attach muscles to bone Ligaments attach bone to bone joints FORMED BY MOST MUSCLES AND BONES IN HUMAN BODY ARE EXAMPLES OF HINGES WITH A POOR LEVEL System, working at a mechanical disadvantage ---- The muscle creates a force equal to 6x the weight of the object in the hand Important feature of Skeletal muscle: Skeletal muscles store large amounts of glycogen and require alot of O2 and have their own O2 storage molecule, myoglobin -Myoglobin is basically one subunit of a hemoglobin molecule capable of holding one O2 molecule -Mature skeletal muscle cells are suspended in Go phase and do not divide
Tight Junctions
Water-proof barriers membranes of neighboring cells are actually fused forming continuous belts around cell to prevent leakage of extracellular fluid found in the epidermis of the skin (although the many layers of dead, keratinized cells also provide a barrier function) and, in "tight epithelium" such as the lining of the bladder, the linings that form the blood-brain barrier, the distal convoluted tubule, and collecting duct of the kidney, etc
Tubulin
a globular protein that polymerizes to form microtubules
Cytoskeleton
a scaffolding-like network of microfilaments, microtubules, and intermediate filaments that provides structure to the cell and creates a highway of sorts for intracellular transport
nucleosomes
a set of eight histone proteins in a cube shape with DNA coiled around it much like thread wound around a spool. There is further coiling and supercoiling of the nucleosomes to create the final condensed chromosome
Immune System Proteins
antigens, antibodies
surface proteins
are contained entirely on the polar surface of the membrane, oppisote of integral proteins
Gastrulation
at about week 2, cells migrate to form the three germ layers
p I neutral
average of pKa-amine group and pKa-carboxyl group This is for neutral amino acids, think of the amino acids that are hydrocarbons
Anaphase I
begins when the two chromosomes of each bivalent (tetrad) separate and start moving toward opposite poles of the cell as a result of the action of the spindle. Notice that in anaphase I the sister chromatids remain attached at their centromeres and move together toward the poles.
Starch
branched, alpha linked glucose polymer, used for energy storage in plants
Deoxyribnoculease
catalyze the hydrolysis of RNA and DNA respectively.
Prophase I
chromosomes become visible, crossing-over occurs, the nucleolus disappears, the meiotic spindle forms, and the nuclear envelope disappears.
Bacterial Shape: Cocci
cocci are spherical bacteria
Parasympathetic Nervous System (Heart)
decreases heart rate and blood pressure.
Deletion Mutations
deleting a nucleotide from a sequence
Ribonuclease
digests RNA catalyze the hydrolysis of RNA and DNA respectively.
Fluid Mosaic Model
dual-layer model of a phospholipid membrane with which students are likely familiar—specifically that there are two opposite-facing leaflets with the polar tails of the phospholipids directed toward the center of the bi-layer and the polar heads directed outward—creating both a cytosolic and an extracellular face. The "fluid" term refers to the fact that phospholipids are mobile—they can exchange positions with each other and move laterally across their leaflet of the membrane
Molecular Cloning: Restriction Endonucleases
enzymes that cut DNA at specific pre-determined sequences. They are used in DNA cloning to create DNA fragments with "sticky ends" that can be hybridized with vector DNA to form recombinant DNA the endonuclease ONLY cuts at one sequence, any fragment cut by that same enzyme will be complementary to any other fragment
Vitamin K
fat-soluble vitamins the human body requires for complete synthesis of certain proteins that are prerequisites for blood coagulation and which the body also needs for controlling binding of calcium in bones and other tissues. vitamin K-related modification of the proteins allows them to bind calcium ions, which they cannot do otherwise. Without vitamin K, blood coagulation is seriously impaired, and uncontrolled bleeding occurs. Low levels of vitamin K also weaken bones and promote calcification of arteries and other soft tissues The picture is vitamin K1
Primary Response
first time your body sees that antigen the immune system's first exposure and reaction to a pathogen.
Binding Proteins
hemoglobin, calmodulin, troponin, tropomyosin, histones, transcription factors, cell adhesion molecules
Mendelian Genetics: Heterozygous
heterozygous genotypes are represented by Bb (carrier genotype)
Semi-Conservative
in each new DNA double helix, one strand is from the original molecule, and one strand is new refers to the fact that each of the newly formed daughter helices consists of one original strand paired with one newly-replicated strand
Gabriel Synthesis
in this reaction, amino acids can be synthesized from potassium phthalimide and diethyl bromomalonate
Sympathetic Nervous System (Heart)
increases heart rate and blood pressure.
Juxtaglomerular Apparatus
juxtaglomerular apparatus detects decreased blood pressure in the afferent arteriole, it secretes Renin, setting into motion the renin -angiotensin pathway whose ultimate result is increased blood volume and blood pressure (this increased blood pressure would provide negative feedback inhibition to the juxtaglomerular apparatus) in the nephron, the complex of cells from the distal tubule and the afferent arteriole which helps regulate blood pressure by secreting renin in response to blood pressure changes in the kidney; located near the glomerulus
phospholipids
lipid molecules with non-polar tail regions and a polar phosphate heads. This polarity is pivotal to their function in membranes. They will need to be able to draw out a phospholipid in line-bond form, understanding all functional groups and connections
B-cells
lymphocytes that mature in the bone marrow and lymph tissues and participate in humoral immunity. B-cells produce antibodies, T-cells do not. T-cells recognize and bind antigens via a "T-cell Receptor" (TCR) not found on B-cells
T-Cells
lymphocytes that mature in the thymus and participate in cell-mediated immunity T-cells recognize and bind antigens via a "T-cell Receptor" (TCR) not found on B-cells cells which recognize and respond to particular pathogens, mature in the thymus
The reproductive System
male and female penis, testicles, scrotum, sperm, seminiferous tubules, epididymis, vas deferens, seminal vesicles, prostate gland, bulbourethral gland, and urethra vagina, cervix, uterus, fallopian tubes and ovaries
Mast Cells
mast cells are permanent resident cells within many tissues. They are activated by allergens and other antigens to release histamine and other chemical mediators. They are usually associated with severe allergic reactions, including anaphylactic shock.
The Endosymbiotic Theory
mitochondria evolved from aerobic prokaryotes that were engulfed by a larger "host" prokaryote. The two bacteria began to form a symbiotic relationship. The presence of the double bilayer membrane, the fact that mitochondria have their own DNA, that they replicate their own DNA, and that they divide and replicate much like a bacterium, are all pieces of evidence in support of this theory.
Cleavage
mitosis without change in size The process of cytokinesis in animal cells, characterized by pinching of the plasma membrane; specifically.
The Musculoskeletal System
movement, support, and stabilization, generation of heat, aide to circulation, maintenance of homeostasis
Cancer: Carcinogens
mutagenic chemicals that cause or promote cancer.
Translocation Mutations
mutation in which one part of one chromosome breaks off and attaches to another
haploid
n chromosome haploid cells have only one. The value of n varies among species, for humans it is 23, therefore all human diploid cells, being 2n, have 46 chromosomes.
Granulocytes
neutrophils, eosinophils, and basophils. These cells live for hours to days. B.E.N Basophils. Eosinophils. Neutrophils
Secondary Active Transport
no direct coupling of ATP required transport of molecules across the cell membrane utilizing energy in other forms than ATP. This energy comes from the electrochemical gradient created by pumping ions out of the cell. This Co-Transport can be either via antiport or symport Antiports and symports Secondary active transport is a form of active transport across a biological membrane in which a transporter protein couples the movement of an ion (typically Na + or H +) down its electrochemical gradient to the uphill movement of another molecule or ion against a concentration/electrochemical gradient.
Pinocytosis
non-specific endocytosis of extracellular fluid and very small particles and occurs it occurs in all cells The key differentiator is that pinocytosis is non-specific This is in contrast to receptor-mediated endocytosis in which the cell binds a specific target for uptake
Cartilage
o A connective tissue composed mostly of collagen. o No perfusion or innervation o Found in appendages such as the nose and ears, at the ends of long bones, between vertebrae, and at almost any joint or articulation
Blood Vessels
o Arteries -> Arterioles -> Capillaries -> Venules -> Veins Arteries: muscular, thick-walled vessels that push blood through via rhythmic contraction. Veins: thin-walled vessels with little to no musculature, relies on valve system to get blood back to the heart
Microtubules
one of three primary contributors to the cytoskeleton of the cell, microfilaments (actin polymers) and intermediate filaments being the other two. Microtubules are conveyer belts inside the cells. They move vesicles, granules, organelles like mitochondria, and chromosomes via special attachment proteins. They also serve a cytoskeletal role. α-tubulin and β-tubuli are the 2 types, form a heterodimer and is assembled into long chains called protofilaments If microtubules aren't working we would have: weak cytoskeltons, lost function of pathways for intracellular transport, unseccesful mitosis or meiosis, ciliated epithelial cells lose function, infertility Microtubules are found in all the places listed above (because cilia contain them), in the flagella of sperm, and in all cells as part of the cytoskeleton and spindle apparatus. 13 of these protofilaments surround a hollow core, form one microtubule The 9+2 arrangment is only found in eukaryotic cilia and flagella, 9 refers to doublets (2 microtubules each) surrounding a center doublet of 2 microtubles, in total 20 microtubles
Lysosomes
pH of 5 digest cell parts, fuse with phagocytotic vesicles, participate in cell death (apoptosis), etc.; lysosomes form by budding from the Golgi
Endocytosis
process by which a cell takes up small particles by invagination of the plasma membrane to form a vesicle called an endosome
Exocytosis
process by which a vesicle on the inside of the plasma membrane fuses with the plasma membrane, dumping its contents into the extracellular environment
Red Bone Marrow
produces red and white blood cells and platelets found in cancellous bone; site of hematopoiesis
histones
proteins around which the DNA helix is wrapped during the first step of DNA condensation to form a chromosome
integral proteins
proteins that have one or more moieties (i.e., segments) embedded within the phospholipid bilayer.
Gas Exchange and Hemoglobin
quaternary protein made of four protein chains, two alpha and two beta. Each protein has an Fe containing "heme" group at its center. Each heme can hold one O2 molecule. Maxiumum O2 is 1 for each protein, so for hemoglobin, the maxium oxygen molecules held is 4
natural Killer Cells
recognize infected or cancerous cells and release cytotoxic granules that destroy the cell
Bidirectional
refers to the fact that replication proceeds in both directions simultaneously from the origin
Cancer: Malignant
refers to tumors that are cancerous—meaning they are currently exhibiting uncontrolled growth and are likely to metastasize, etc
Cancer: Benign
refers to tumors that are still slowly growing, have not invaded other tissues, but could become cancerous later on
centromere
region of the chromosome that joins the two sister chromatids
Lipid-soluble hormones
require a protein carrier or a micelle/vesicle. Lipid-soluble hormones act almost exclusively by binding to a receptor on or inside the nucleus and influencing transcription Lipid-soluble hormones diffuse easily through the lipid center of the membrane and thus do NOT require a cell membrane receptor. They still require a receptoreventually, wherever they act inside the cell
Suppressor T-cells
responsible for ending the cell-mediated immune response after an infection has been brought under control AKA regulatory T-cells. Help to tone down the immune response once infection has been adequately contained. Turn off self-reactive lymphocytes to prevent autoimmune diseases. regulatory T-cells) suppress the body's own immune system—which helps prevent severe allergic reactions or autoimmune disease and aids in turning off an immune response once an infection has been eliminated.
Vitamin D
responsible for increasing intestinal absorption of calcium, iron, magnesium, phosphate, and zinc. FAT SOLUBLE
Peroxisomes
self-replicate, detoxify chemicals, participate in lipid metabolism.
Memory T-cells
serve a similar function to memory B-cells Lymphocyte that has previously encountered an antigen and that on re-exposure to the same antigen rapidly initiates the immune response analogues to memory B-cells that have previous experience with a pathogen that allows them to mount a more effective response during a subsequent infection
Mutations: Silent
silent mutation is any mutation that does NOT alter the amino acid sequence. This could be because the codon was changed from one codon that codes for an amino acid to one of the other codons that also codes for that same amino acid (i.e., degeneracy/redundancy of the code). Mutations in an intron would also be considered silent mutations
Prokaryotic Flagella
spinning/rotating motion; simple helices made of flagellin Proton Driven Smaller and simple structure
Bacterial Shape: Spirilla Bacteria
spirilla are spiral-shaped bacteria
Yellow Bone Marrow
stores fat
spindle apparatus
structure made of spindle fibers, centrioles, and aster fibers that is involved in moving and organizing chromosomes before the cell divides
Sulfur Linkage
sulfur linkage of two cysteins
Killer T-Cells
target infected and cancerous versions of the body's own cells and destroy them Kills cells that have been infected
Secondary REsponse
the immune system's response to that same pathogen during subsequent exposures. other time your body sees that antigen
Non-competitive inhibition
the inhibitor binds the enzyme whether or not the substrate is bound and does not bind the active site. Noncompetitive inhibitors decrease vmax while having no effect on Km! Vmax decreases, Km stays the same. Example: Alanine acts as a non-competitive inhibitor for the enzyme pyruvate kinase. Pyruvate kinase transfers one phosphate group from PEP (phosphoenolpyruvate) to ADP, creating pyruvate and one ATP. Alanine can bind to pyruvate kinase (whether or not PEP is bound) to inhibit activity, creating a negative feedback loop (because alanine synthesis derives from pyruvate).
Sperm
the male haploid gametes. They are produced in the seminiferous tubules of the testes and move to the epididymis, where they are nurtured, fully matured, and stored until ejaculation. Acrosome- is a membrane-bound structure on the tip of the head of each sperm. The acrosome contains hydrolytic enzymes that break down the otherwise impenetrable coating around the ovum.
Prophase
the nuclear membrane degenerates and the chromosomes condense.
Penis
the penis is the male copulatory organ. It can also be thought of as playing a dual role in excretion and ejaculation because the urethra runs through it.
Meiosis II
the second phase of meiosis consisting of chromatids separating, along with the two diploid cells splitting in two
Cancer: Metasis
the spreading of a cancer from one tissue or organ to another
phospholipid at the molecular level
tudents will need to be able to visualize and draw a phospholipid at the molecular level. This includes the understanding that they are formed by combining a glycerol molecule with two fatty acids and one phosphate
homologues
two related but non-identical chromosomes—one originating from each parent.
sister chromatids
two strands of DNA in a duplicated chromosome attached by a centromere, only exists have replication Assuming no mutations or errors in replication, they are identical as long as crossing over has not yet occurred
Phagocytosis
type of endocytosis specifically referring to the engulfing of very large particles, bacteria, etc., and only occurs in some cells Phagocytosis is always receptor-mediated.
kinetochore
used synonymously with centromere, but they are not identical. The centromere is a region on the chromosome and the kinetochore is a specialized group of proteins to which the spindle fibers attach directly during mitosis/meiosis
Virus
viruses are acellular and cannot survive, grow, or reproduce on their own. They require a host to accomplish most if not all of the functions we normally associate with "living things." AKA ZOMBIES! Viruses always contain some form of nucleic acid (DNA or RNA, but never both) plus proteins.. Viruses multiply much faster than bacteria.... Enveloped viruses, such as the cold virus and HIV, are small spherical membranes surrounding a protein capsid and the nucleic acid (as shown below). Retroviruses always contain RNA, and therefore must also contain a specific enzyme called reverse transcriptase capable of translating this RNA nucleotide sequence into DNA (because RNA could not be incorporated into the host's genome).
Immune System Cell pathway
we strongly suggest you forget about memory T-cells for the MCAT! As far as the MCAT is concerned, the concept of immunological "memory" and a "secondary immune response" are so intricately associated with humoral immunity that the wisest choice would be to always associate such concepts with B-cells and humoral immunity only. The algorithm below can help you put together a mental picture of where all of these cells come from and how they relate. You should NOT concern yourself with the progenitor cells. Just focus on the final step of each pathway and perhaps the precursor just before it. For example, it is helpful to observe things such as: a) multiple non-nucleated RBCs form from a single parent cell, b) the three granulocytes are related because they all differentiate from one parent cell, c) platelets (thrombocytes) bud from megakaryocytes, or d) monocytes differentiate into macrophages. Not shown on this diagram are dendritic cells, which can form from either a monocyte or from another cell that is a precursor to lymphocytes.
Duplication mutations
when a segment of DNA is copied multiple times in the genome
Mendelian Genetics: True-Breeding
...A true-breeding organism, sometimes also called a purebred, is an organism that always passes down certain phenotypic traits (i.e. physically expressed traits) to its offspring. An organism is referred to as true breeding for each trait to which this applies, and the term "true-breeding" is also used to describe individual genetic traits. In Mendelian genetics, this means that an organism must be homozygous for every trait for which it is considered true breeding; that is, the pairs of alleles that express a given trait are the same. In a purebred strain or breed, the goal is that the organism will "breed true" for the breed-relevant traits
Natural Selection
1) One individual must have a polymorphism that provides an evolutionary fitness advantage. 2) That advantage must result in the individual with the favored polymorphism differentially producing more offspring.
Genes are regulated via three basic mechanisms
1) Rate of transcription: RNA has a short half-life, so gene products will only continue to be expressed if DNA is continually transcribed. 2) Activators and Repressors: Regulatory molecules may upregulate DNA transcription (e.g., lactose in the Lac Operon) or downregulate DNA transcription (e.g., glucose in the Lac Operon). These regulatory molecules are often hormones, products of the reaction or cascade that is catalyzed by the gene product, byproducts that build up when the concentration of the gene product is low, etc. 3) Permanent or Semi-Permanent Suppression: Methylation or other covalent modification that prevents or dramatically decreases transcription.
The Diaphragm
1) The diaphragm moves down when it is flexed and moves up when it is relaxed. -When relaxed it has an upward-oriented convex shape. When flexed it is almost flat. 2) The diaphragm moves down during inhalation and up during exhalation.
Oxygen Dissociation Curve
A graph of % Hemoglobin Saturation vs. pO2 an important tool for understanding how our blood carries and releases oxygen. relates oxygen saturation (sO2) and partial pressure of oxygen in the blood (pO2)
Epithelial Tissue
A body tissue that covers the interior and exterior surfaces of the body. cover the body or line its cavities. Epithelium is a general term, and some specific types are the epidermis of the skin, the endothelium of blood and lymph vessels, and the mesothelium that lines thoracic and abdominal cavities if it is lining a cavity or separating the body from the external environment, you can consider it to be epithelial tissue , epidermis, skin, Pseudostratified epithelieum is usually ciliated...
Connective Tissue
A body tissue that provides support for the body and connects all of its parts bone, cartilage, blood, lymphatic tissue, fat, etc. It would be fairly safe to assume that if a cell is not clearly part of one of the other three classes it is most likely connective. These include blood, lymph, tendons, ligaments, adipose tissue, the nonepithelial wrappings, coverings, and support tissue found around muscles and organs, and so forth. 5 types- adipose, collagen, bone, red blood cells, cartilage Most organs, for example, have a considerable amount of connective tissue interspersed with muscle tissue, nerve tissue, and epithelial linings dermis, adipose tissue blood, bone, ligament
Zwitterion:
A dipolar version of an amino acid wherein positively and negatively charged functional groups cancel one another out, resulting in a neutral ion. With the exception of amino acids that have charged -R groups (Asp, Glu, Lys, Arg, His), ALL of the amino acids exist as Zwitterions at a pH of 7.4 Below a pH of about 9 the amine group will be protonated: -NH3+. Above a pH of 9 the amine group will be - NH2 (as shown in most texts), but at that very high pH the carboxyl group will have long ago been deprotonated: -COO- (pH ~ 2).
Action Potential
A disturbance (i.e., a dramatic change) in the resting electrical potential (i.e., voltage) across the membrane of a nerve cell. Once an action potential is created, it will propagate along the cell membrane to neighboring portions of the neurons. As it does, the areas where it originally started gradually return to the normal resting potential
Lineweaver-Burk Plots
A double-inverse graph of the Reaction Rate (v inverted to 1/v) and substrate concentration ([S] inverted to 1/[S]) graph described above. Describes how rate of reaction depends on concentration of enzyme and substrate; linear Y-Intercept = 1/Vmax - As Vmax Increases, Y Intercept decreases - As Vmax decreases, Y intercept increases X-Intercept = -1/Km - As Km increases, X intercept decreases -As Km decreases, X intercept increases Used to calculate Vmax and Km experimentally Used to identify Enzyme Inhibition: ---Because these two values can be easily calculated from the x- and y-intercepts of a Lineweaver-Burk plot, the type of enzyme inhibition can be easily deduced. To do so, you must have two trials, one with, and one without, the inhibitor. ---By comparing these two results you can observe the IMPACT of the inhibitor on Km and vmax, and therefore deduce the type of inhibitor.
Divergent Evolution
A form of evolution in which the same organism is placed into different environments with different selection pressures. This causes organisms to evolve differently, to diverge from their common ancestor. The resulting (new) species may share structural (but not necessarily functional) similarity; divergent evolution produces homologous structures. Divergent evolution is the process by which species develop different forms AND thereby form new species, all radiating from that common ancestor. Adaptive radiation is an example of rapid divergent evolution.
Mutations: Frameshift
A frameshift mutation (also called a framing error or a reading frame shift) is a genetic mutation caused by indels (insertions or deletions) of a number of nucleotides in a DNA sequence that is not divisible by three.
The Neuron
A neuron is a specialized cell that can carry an electrochemical signal (i.e. action potential). o Remember that neurons: 1) Are frozen in G0 phase (unable to divide) 2) Depend entirely on glucose for energy, thats why when we are not eating well, we go CRAZY and harder to think straight, so get a good breakfast 3) Don't require insulin for glucose uptake 4) Have very low glycogen & oxygen storage capability and thus require high perfusion (blood flow), thus why we always need constant blood flow.
Mutations: Neutral
A neutral mutation is any mutation that does not negatively impact the fitness of the individual. Theoretically, any of the above types of mutations could be silent, although it is reasonable to assume that most nonsense or frameshift mutations will cause too much alteration to the protein for it to remain function. Nonsense or frameshift mutations will cause deletion!
Collecting Duct
A number of DCTs from a number of different nephrons dump into a shared collecting duct. The collecting duct carries the filtrate through the medulla toward the renal pelvis. The collecting duct becomes very permeable to water in the presence of ADH from the posterior pituitary. If ADH is present the filtrate will be further concentrated as water flows out into the very salty medulla. the location in the kidney where processed filtrate, called urine, is collected from the renal tubules
Mutations: Point
A point mutation is a single base pair substitution
Vaccines
A vaccine is an inactive virus, or portion of a virus, delivered to a person so that their immune system can develop antibodies against the virus without the host experiencing an actual viral infection. Upon exposure to the viral proteins, the immune system will create memory B-cells with antibodies that match the viral proteins. If this host is later infected with that same virus, these B-cells will differentiate into plasma cells that rapidly produce and release antibodies for the virus. Vaccines tend to lose effectiveness over time because viruses mutate at a rate that is faster than any known living thing.
Citric Acid Cycle
Acetyl CoA is the first substrate of the Krebs or TCA. It comes from Pyruvate as a result of PDH enzyme complex. It is also a product of Beta oxidation of fatty acids and from amino acid metabolism (protein origin). Occurs in the matrix of mitochondria Know what species go in and out of the cycle and where they come from and where do they go next Know the starting substrate and final product of each step Number of cycles per glucose, number of Co2 produced - 2 cycles per glucose (2 pyruvate) - citric acid cycle produce six CO2 molecules, 10 NADH molecules, and two FADH2 molecules per glucose molecule Know how the Carbon Skeleton changes Goes through substrate levelphosporylation
DNA Nucleotide
Adenine Nucleotide
acetylcholinesterase
Agonist vs Antagonist An acetylcholinesterase antagonist would impede the normal activity of this enzyme, which breaks down acetylcholine. Decreased breakdown of the neurotransmitter would allow more of it to be present in the synaptic cleft, and to be present for a longer period of time—causing hyperstimulation of the subsequent neuron. Hyperstimulation of neurons could cause any number of problems depending on the effector with which a neuron is communicating. Muscle rigor, cramping, ticks, and pain would be logical possibilities. The drug effect would not necessarily be negative. An increase in the concentration of certain neurotransmitters in the brain has been shown to combat depression and therefore many antidepressants are actually acetylcholinesterase inhibitors (i.e., fluoxetine [Prozac], sertraline [Zoloft] and amitriptyline [Elavil]). If the drug were an agonist it would have the opposite effect, resulting in increased breakdown of acetylcholine and therefore decreased stimulation of neurons.
Motor Unit
All of the fibers in a skeletal muscle do NOT fire simultaneously during a contraction A group of muscle cells innervated by a single motor neuron is called a motor unit and they come in different sizes and large to small Delicate movements use small motor units Gross movements use larger motor units Strength of Contraction Depends on: 1) Number of motor units being used 2) size of the motor units being used 3) frequency of action potentials (stimulation)
Making Predictions
Always draw out the Punnett Square Important Convention: Homozygous dominant is assumed for an individual with the dominant phenotype. If an individual is a carrier for a recessive allele (heterozygote), or is affected (homozygous recessive), that fact will always be clearly stated. Some questions may ask you to predict the genotype of offspring when you are only given information on one of the parents. By convention, you assume the other parent is NOT affected and is NOT a carrier. Wild Type = The normal or typical phenotype.
Acid-Base Functionality of Amino Acids
Amino ACIDS are weak ACIDS amino acids exhibit the same general acid-base functionality, thus they are very stable, thus their stabilizing effect on enzymes and proteins Each amino acid has a minimum of 2 acidic protons, -COOH and -NH3+ Amino Acids act as a buffer when the pH is near the pKa of one of the acidic protons
Proteins
Amino Acid Polymers Amino Acids= Residues Oligopeptide- Very small chain of amino acids Polypeptide- Longer chain of Amino Acids
Protein Metabolism:
Amino acids can be broken down to pyruvate or acetyl-CoA to go to CAA. Other Amino acids can be formed into stuff for CAA Transamination: Key step to change amino acids for protein metabolism, it is the exchange of an amine group on one molecule for a carboyl group on another Ketogenic vs GLucogenic Amino Acids - Ketogenic--- Degraded into Acetyl CoA or ketone body via ketogensis, ultimately converted to Co2 in CAA, Leucine and Lysine are ketogenic - Glucogenic--- Amino acids -> glucose through gluconeogensis, via first to alpha keto acids then to glucose in liver. -SOme AA are both: ILE, PHE, TRP, TYR, THR Ketogensis vs Ketolysis -Keotgenesis= process which Ketone bodies made through breakdown of fatty acids, occurs in periods of starvation when low glucose levels and no carb fuel available. Provivdes energy in liver via Acetyl CoA to CAA - Ketolysis= Use of ketone bodies from acetyl CoA to energy, occurs i nother organs than liver , usually heart and brain. Liver doesn't have enzyme to utilize KB for energy. -When blood glucose ↓, Beta Oxidation and Ketogensis will happen in the liver to be transported to key tissues for energy via ketolysis. Our brain and CNS need it the most during starvation
Alpha glucose vs Beta glucose
Anomers Always have ame name
Mendelian Genetics: Allele
An allele is one of various alternative forms of the same gene. For example, if hair color is determined by a single gene at a single locus, that segment of DNA would be the "hair color gene." One version of that gene (i.e., one allele) might produce blonde hair, while another variation in the sequence at that segment (i.e., a second allele) might produce brown hair, and so forth
Zymogens
An inactive enzyme precursor. an inactive substance that is converted into an enzyme when activated by another enzyme. Example- Prothrombin is a zymogen. It is an inactive enzyme precursor that is activated by prothrombinase, which converts prothrombin to thrombin, a vital enzyme in the blood coagulation cascade. Zymogens are incredibly important in the body. They are often the precursors for enzymes that are needed quickly but that would be detrimental if active all the time. Others include chymotrypsinogen and trypsinogen, precursors to proteases, and pro-caspaces, which are essential to the apoptosis pathway. You don't want free, activated proteases in a cell, because they would degrade random proteins, and you definitely don't want the apoptosis pathway activated randomly. However, with zymogens, cells essentially have these enzymes "on call." They are already synthesized and ready to use, they just need to be activated when needed.
Heterotroph
An organism that obtains organic food molecules by eating other organisms or substances derived from them. Heterotrophs, by contrast, cannot fix CO2 and therefore must ingest organic molecules such as carbohydrates as their carbon source
Non-Template Synthesis
Anabolism of Fats & Carbohydrates: --- Anabolisn is opposite of acatabolism, is is syntheis= makes larger macromolecules out of smaller precursors --- Catabolic breaks down Non-Template Synthesis - Biostynehsis of lipids and polysaccharides (carbohydrates).. - Moniker non template is used cause synthesis of fats and carbs don't follow same pattern as protein and nucleic acid synthesis
Fermentation
Anaerobic GLycolysis MOst bacteria use this as the only route to metabolize glucose Fermentation is normally used by animals only when there is oxygen debt and in erythrocytes Erythrocytes->Mature erythrocytes lack cellular organelles, they are basically sacks of hemoglobin. This means they also lack mitochondria, the normal location of the citric acid cycle, ETC, and oxidative phosphorylation. Red blood cells use fermentation—even in the presence of oxygen—because they lack the cellular machinery found in other cells and therefore fermentation is their only route to produce energy. Fermentation is IMPORTANT because it regenerates NAD+ so that glycolysis can continue. NAD+ regeneration is necessary for both human fermentation during oxygen debt and yeast/bacterial fermentation.
Anaphase
Anaphase is indicated by separation of the chromosomes and migration toward the opposite poles of the cell. Phase of mitosis in which the chromosomes separate and move to opposite ends of the cell
Humoral Immunity
B Cell immunity or antibody-mediated immunity specific immunity produced by B cells that produce antibodies that circulate in body fluids Involves B-cells, which is ALWAYS humoral immunity- B-Cell=Anti body= humoral immunity B-Cells develop in the bone marrow and mature there or in lymph tissue each b-cell produces only one specific protein receptor on it's membrane called an antibody Each antibody will recognize and bind with only one foreign particle called an antigen If an antigen binds to a b-cell's antibody, the b-cell will undergo differentiation into a plasma cell and a memory b-cell. The plasma cells manufacture free antibodies and release them into the blood. The memory B-cells multiply and remain the blood, preparing the body for a secondary response.
Basophils
Basophils are the least common white blood cell. Their granules contain mostly histamine, which they release along with other chemicals when activated. These chemicals promote inflammation and are integral in the allergic response, so many associate basophils will allergies.
Short DNA Helix
Be sure students can visualize and easily draw all bond-to-bond connectivity—especially the phosphate bond between the 3' hydroxyl group and the 5' carbon, and the hydrogen bonds between bases general familiarity is helpful solidify the concept of how hydrogen bonds form between these bases The AAMC has frequently required knowledge of the actual bond-to-bond connectivity, and/or the functional groups involved in the DNA helix. Therefore, it is imperative that students can precisely draw the polymerized nucleotides that make up a section of DNA. It all occurs as hydrogen bonding
Repolarization
Because there are more potassium ions inside the cell (due to the Na+/K+ pump), opening of the potassium channels causes K+ ions to flow out of the cell. This results in a sudden decrease in the membrane potential from +40mV back down to -70 mV, and is referred to as "repolarization."
Biological Oxidation-Reduction Reactions
Biological REDOX reactions follow all of the same basic science principles as the REDOX reactions you studied in the General Chemistry chapters Half Reactions: Separation of a complete rxn into oxidation and reduction half-reactions, an example of this is step 6 of glycolysis GADP + NAD+ + Pi -> 1,3 BPG + NADH ---In the reaction, GADP is the reduced form, NAD+ is the oxidized form 1,3 BPG is the oxidized form, and NADH is the reduced form. Thus NAD+ is being reduced (it is an oxidizing agent) and GAPD is being oxidized (it is a reducing agent). In biology, oxidation is losing H+ atoms and reduction is gaining H+.... follows the same notion that when something gains H+, it gains the H+ electrons as well. When you see: NADH/NAD+, NADPH/NADP+ FADH2/FAD, FMNH2/FMN, semiquinone (an FMNH* radical), ubiquinone, or cytochrome, THINK: REDOX! These are soluble electron carriers and as they pass from one form to the other there is ALWAYS electron transfer and therefore oxidation-reduction.
Pulmonary Circulations
Blood flows from the right ventricle through the pulmonary arteries to the lungs and back through the pulmonary veins to the left atrium. Oxygen saturated blood returns to the heart via through the pulmonary veins
Pluripotent
Cells can give rise to all of the cell types that make up the body, but not extraembryonic cells. Undifferentiated embryonic stem cells are considered pluripotent.
Plasma cells
Cells that develop from B cells and produce antibodies. formed when a B-cell binds its matching antigen and is activated (with the help of helper T-cells) to undergo mitosis. The division of the B-cells produces mostly plasma cells—clones of the original B-cell that act as "antibody factories," making and secreting soluble copies of that antibody.
Cell Communication
Cells, tissues, and organ systems can communicate with each other in several ways Endocrine, Paracrine, Autocrine, Intracrine, Juxtacrine, Nervous System
Hemoglobin
Classic Example of Quaternary STructure 4 protein chains, 2 alpha and 2 beta subunits Each heme can carry one O2 molecule Positive Cooperativity = Ligand affinity increases with the binding of each subsequent ligand. In the case of hemoglobin, affinity for the first oxygen is relatively low, but increases for the second, third, and fourth oxygen to bind. This affinity remains in effect during offloading of oxygen at the tissues. Therefore, the first oxygen (highest cooperative affinity) dissociates at the slowest rate, but each subsequent oxygen is released more easily.
Rough ER (RER)
Covered with ribosomes that are actively translocating proteins into the ER lumen as those proteins are translated all proteins bound for the ER itself, the Golgi, lysosomes, endosomes, the plasma membrane, or secretion outside of the cell (plus some proteins bound for other organelles), are made at the RER All proteins bound for the cytosol, plus some proteins bound for other organelles, are made on free-floating ribosomes in the cytosol Post-translational modification starts here (disulfide bonds, glycosylation, etc.) and continues in the Golgi
When does crossing over occur and why is it important?
Crossing over occurs during prophase of meiosis I. Two homologous dyads pair up with one another and exchange segments of DNA. Crossover events occur at a high rate. In fact, crossing over happens to such an extent that two genes must be very close to one another on the chromosome to avoid the nearly inevitable likelihood that a crossover event will separate them. This is why genes located on the same chromosome can still assort independently, as do genes on separate chromosomes. Genes close enough to each other on the chromosome that being separated by a crossover is less likely are said to be linked. If crossing over did not exist, we would say that all of the genes on one chromosome are linked.
Mechanisms of DNA Repair: Proofreading
DNA polymerase exhibits a substantial proofreading function that catches and repairs most mismatched base pairs on the spot
DNA Replication
DNA replication begins at an origin of replication. Helicase unzips the double-helix. Immediately, single-strand binding proteins coat the individual strands and prevent them from re-annealing. Next, both strands are simultaneously fed through a replication complex that contains all of the proteins necessary for replication. Because DNA polymerase can only add to an existing 3' OH group, primase (an RNA polymerase) first constructs short RNA primers on both strands. Two DNA polymerase molecules then begin building new complementary DNA strands. In doing so, they must "read" (i.e., move along the strand) in the 3' to 5' direction, building the new strands in the 5' to 3' direction. The sliding clamp is a protein that helps keep the DNA polymerase tightly associated with the strand. Because both enzymes must move along the strand in the 3' to 5' direction, they move in opposite directions. If this continued indefinitely, the two enzymes would move farther and farther apart. Instead, all enzymes and proteins remain closely associated with the replication fork in what is often called the "replication complex." As a result, the enzyme working on the lagging strand must copy short segments downstream, release from the strand, move upstream, and copy another short segment downstream, and then repeat. This also means that while the leading strand requires only a single primer, the lagging strand requires multiple primers, one for each of these short segments called Okasaki fragments. After this initial replication step, the enzyme RNase H removes all RNA primers. DNA polymerase then fills in the gaps. However, remember that DNA polymerase can only add nucleotides to existing 3' OH functional groups. Therefore, although it can add a nucleotide to fill the last missing base pair in a gap, it cannot connect that last nucleotide to its downstream neighbor. This functionality is performed by DNA ligase. DNA ligase creates the last necessary phosphodiester bond, completing the strand. https://www.youtube.com/watch?v=dKubyIRiN84
Absoprtion- Proteins
Digestion begins in the stomach and is complete by the end of the small intestine. Proteins are broken down to small peptides and amino acids before absorption. They enter the bloodstream (NOT the lacteal) and travel to the liver.
Dihybrid Crosses
Dihybrid Crosses: When two traits are being considered, draw out two independent Punnett Squares, one for each trait. To calculate the probability of having two traits in the same individual, multiply the individual probabilities for each trait. If the number of individuals with a specific genotype or phenotype is asked for, multiply the total probability of having both traits by the total number of offspring. in a dihybrid cross you should get a 9:3:3:1 phenotypic ratio
The Egg
Eggs are the female gametes. Their plural scientific name is ova and the singular form is ovum. An egg begins meiosis as a germ-line cell in the ovary of a female fetus and is arrested at Prophase I of meiosis at birth. Not until puberty and menstruation is Meiosis I completed. Even then, all cells remain in this arrested state except for those that begin maturing in a follicle in preparation for ovulation. Meiosis II is not completed until after the sperm fertilizes the ovum. An immature egg is called an oocyte.
Eosinophils
Eosinophils are recruited to areas of parasitic invasion, particularly multicellular parasites, where they release their granules containing peroxidases and other enzymes that digest tissue. This would destroy the pathogen but could also destroy host tissue. Note that all granulocytes are short-lived, do not reside permanently in the tissues, circulate in the blood, and are recruited to areas of infection of inflammation.
Skin
Epidermis: --- The outermost layer is avascular and made up of mostly dead or dying, keratinized cells Dermis: --- Contains blood vessels, hair follicles, sebaceous glands, sudoriferous/sweat glands, and nerve endings --- CONNECTIVE TISSUE Thermoregulation: --- Blood vessels closer to surface of skin dilate when heat needs to be released and constrict when heat needs to be retained- ex- blushing --- Arrector pili muscles cause erection/ goose bumps of hair follicles, generating heat and traps insulating layer of air next to skin --- Subcutaneous fat provides insulation --- Sweating, followed by evaporation of water, carries away heat due to high heat of vaporization and specific heat capacity
non-Mendelian inheritance patterns: Epigenetic
Epigenetic refers to any heritable phenotype resulting from any process other than a change in the DNA sequence itself. You could think of this as any genetic influence that is "outside" of the DNA sequence itself just as Epidermis is on the "outside" of the body
Glucose vs Galactose
Epimers Different Molecules, example of diastereomers Remember, an epimer refers to one of a pair of stereoisomers. The two isomers differ in configuration at only one stereogenic center. All other stereocenters in the molecules, if any, are the same in each. Always different names
New DNA strands are always shorter than parent strand
Every time a DNA strand is replicated, the new strand is always slightly shorter than the parent strand The DNA polymerases require an existing 3' hydroxyl group to which they can add their first nucleotide—they cannot set down a nucleotide with a free 5' end For this reason, an RNA primer must be placed at the 5' end of any DNA strand. Later in the process all primers are removed and the gaps are filled in by DNA polymerase and DNA ligase. At the 5' end, however, there are still no existing 3' hydroxyl group so DNA polymerase cannot replace that section of primer. As a result, every time a chromosome is replicated the new daughter strands will be slightly shorter than the parent strands, by an amount exactly equal to the RNA primers that were in place on both ends of the chromosome
Protein Separation Techniques: Electrophoresis:
Explain Conceptually, including Drawings or figures, the process of separating proteins: Separating proteins by electrophoresis will separate proteins based on size. To perform electrophoresis, proteins are placed in a solution with a detergent to denature them and to coat them uniformly with a negative charge. This gives proteins a uniform charge to mass ratio. Proteins are then run through a gel of polyacrylamide, which will slow down the migration of larger proteins more than smaller ones. The gel is run from the negative to the positive electrode, so the proteins are pulled toward the positive pole due to the negative charge from the detergent. The smallest proteins will run furthest into the gels, while the largest proteins will stay near the top
G-Protein Cascade
First, a hormone or signal molecule binds to an integral protein on one of its extracellular domains—this protein is called a G-protein-coupled receptor or GPCR. This causes a conformational change that activates a cytosolic domain of that same integral protein. Near the GPCR, or at least along the cytosolic face of the membrane, is a G protein made up of an alpha, beta, and gamma subunit. The alpha subunit binds both GTP and GDP. When GDP is bound, the protein is "off" and when GTP is bound it is "on." Usually, but not always, the activated receptor protein acts as a catalyst for the replacement of GDP by GTP, activating the alpha subunit of the G protein. The activated alpha subunit then separates from the beta and gamma subunits. The activated alpha subunit acts as an agonist for another enzyme, often adenylyl cyclase. Adenylyl cyclase is an enzyme that catalyzes the conversion of ATP to cAMP plus two molecules of inorganic phosphate (ATP cAMP + 2Pi). Cyclic AMP just happens to be an agonist for Protein Kinase A, which phosphorylates proteins—usually enzymes. Many enzymes are turned on or off through being phosphorylated or dephosphorylated. The cascade can be shut down in various ways. Often the beta and gamma subunits re-bind with the alpha subunit, deactivating them. In other cases GPCR isphosphorylated one or more times, which deactivates it DON'T MEMORIZE, JUST UNDERSTAND GENERAL PATHWAY
Galactose Metabolism
Focus on the following: In multiple steps (UDP = coenzyme) Galactose is converted -> Glucose-1P Phosphoglucomutase converts Glucose-1P -> Glucose-6P (G-6P is then funneled into the 2nd step of GLY)
The Stomach
Food storage, mixing, FIRST STAGE OF PROTEIN DIGESTION. The stomach slows the passage of food through the digestive tract, allowing for complete digestion and absoprtion Proteins in the stomach undergo hydrolysis, a rxn done by enzyme pepsin, and this enzyme starts out as pepsinogen, which is a zymogen 4 stomach Lining Cell types: 1) Mucous Neck Cells 2) Chief Cells 3) Parietal Cells 4) G-Cells
p I acidic
For acidic amino acids average of pKa- acidic R group and pKa -carboxyl group aspartic acid and glutaric acid
Gibbs Free Energy (G)
For the MCAT, think of ΔG° and ΔG°' as essentially the same thing. They are the free energy change at a standard physiological conditions, usually at pH of 7, with the (') referring to physiological pH MOst reactions though are never going to be in these exact conditions From a single number and sign we know a lot about a reaction, including whether products or reactants are more favored, whether it will give off or require free energy, and whether products or reactants will predominate at equilibrium. ΔG = ΔG°' + RTlnQ Endergonic = ΔG is positive = nonspontaneous Exergonic = ΔG is negative = spontaneous
non-Mendelian inheritance patterns: Genetic Imprinting
Genetic Imprinting (a.k.a. Genomic Imprinting) results when one specific gene is expressed differently depending on which parent it originated from
Evolution & Populations: Genetic Drift
Genetic drift is a change in the allele frequency within a population due to random, non-genetic, non-selective factors. A bottleneck would be an example of genetic drift because there is no "fitness advantage" or other factor responsible for the change in allele frequency. For example, if a meteorite struck the earth the question of who survived and who did not would not be a question of fitness, it would be a random result of who happened to be in the meteor's path.
Linkage
Genetic linkage is the tendency of alleles that are located close together on a chromosome to be inherited together during meiosis. Genes whose loci are nearer to each other are less likely to be separated onto different chromatids during chromosomal crossover, and are therefore said to be genetically linked. Genes that are located near each other on a chromosome are called linked genes. They are linked because they travel together during meiosis. This means they get packaged into the same gamete more often than not. The exception to this rule is when recombination occurs and genes are swapped. Q48. Describe the concept of linkage in terms of the distance between genes on the chromosome. Why is relative location on the chromosome important? When we say that two genes are linked we mean that they do not assort independently. In other words, inheriting one gene changes the probability of inheriting the other When you look at chromosomes and consider that they contain many, many genes, and yet are inherited as a single, whole chromosome, we would expect that all of the genes on a chromosome would be linked. This is not the case due to crossing over. Crossing over between chromosomes during Prophase I of Meiosis happens so often that it is as if all of the genes were not riding together on chromosomes, but were individual little segments assorted independently each with an equal and independent probability of landing in one cell or the other. Linkage does occur when two genes are very, very close to each other on the same chromosome because at certain proximity it becomes unlikely that a crossing over event will occur exactly between them.
Tertiary Protein Structure
Geometric, 3D folding of ALpha helices, beta sheets, and other moieties to form a functional globular or structural protein Interactionsdue to side chain interaction The following 6 interactions contribute to tertiary protein structure: 1. Hydrogen bonding - non-covalent bond between either backbone atoms (N-H or C=O) or side chains (amine groups, carboxyl groups, alcohol groups) 2. Disulfide bonds - covalent bond between the sulfurs of two cysteine residues 3. Hydrophobic/hydrophilic interactions - in soluble proteins, the hydrophobic amino acids will collapse into the protein core. In membrane proteins, the hydrophilic membranes will be either outside the membrane in the cytoplasm or inside the core of the protein, away from the membrane bilayer, with hydrophobic amino acids located within the membrane bilayer. 4. Ionic interactions (salt bridges) - charge-charge interactions between a positively charged amino acid and a negatively charged amino acid 5. Van der Walls forces - intermolecular forces that repel atoms away from each other (steric hindrance) 6. Proline turns - because of proline's unusual cyclical shape, introducing a proline into an alpha helix or beta sheet will cause a kink. Proline turns are also found at the end of most strands involves in beta sheets. The sharp turn helps the chain redirect in such a way that the next segment is running anti-parallel to the previous segment in the sheet formation.
Hormonal Control:
Glucocorticoids, catecholamines, T3 and T4 Essentially, when we have alot of the product, it down Glycolysis: -Up-regulate: AMP, low cell energy -Down-regulate: PFK inhibited by high levels of ATP= main source of regulation, ATP Inhibits Pyruvate Kinase, high levels of energy, GLucose 6 Phosphate inhibits hexokinase Gluconeogensis: -Up-regulate: energy levels high, glucose low, stimulated by high ATP -Down-regulate: Fructose 1,6 Biphosphatase inhibited by AMP, Pyruvate carboxylase and PEP inhibited by ADP Glycogenolysis: -Up-regulate: glucagon, Epinephrine, utilizes cAMP cascade for protein Kinase -Down-regulate: low glucagon, epinephrine Glycogen Synthesis: -Up-regulate: low cAMP, oppisotes of glycogenolysis -Down-regulate: glucagon, epinephrine, Citric Acid Cycle: -Up-regulate: low levels of NADH, ATP, isocitrate dehydrogenease stimulated by ADP -Down-regulate: high products of acetyl CoA and NADH, ATP, isocitrate dehydrogenease inhibited by ATP, alpha ketoglutarate dehydrogenase inhibited by products succinyl CoA and NADH and ATP ETC & ATP Synthase: -Up-regulate: High levels of ADP -Down-regulate: High levels of ATP, poisons, Cyanide, azide, CO, oligomycin Pentose Phosphate Pathway: Controlled by levels of NADP+ -Up-regulate: activated by NADPH -Down-regulate: inhbited by NADP+
Glycogen Metabolism
Glycogen Metabolism usually occurs in the liver and in muscles 1- Glycogen Phosporylase removes glucose residues from teh reducing ends of glycogen polymers-> GLucose 1-P 2- Phosphoglucomutase converts GLucose 1P -> Glucose-6P ( G-6P is then funneled into the 2nd step of glycolysis)
Endocrine
Hormone signaling. Hormones are manufactured and secreted by cells in the endocrine glands, travel in the bloodstream, then bind to receptors either on the cell surface (in the case of water-soluble hormones) or inside the cell (in the case of lipid-soluble hormones
Human Taxonomy: Phylum
Humans- Phylum: Chordata The chordates are deuterostomes, have a notochord, dorsal hollow nerve cord, pharyngeal gill slits, and a post-anal tail at some point during development
Predicting Hormone Levels
Hormones always act to return the system to homeostatic, or "normal," conditions. They never cause a drift away from normal. Example: Q27. Recalling that glucagon stimulates the release of glucose into the bloodstream and insulin stimulates the uptake and storage of glucose, answer the following: Patient A has high blood glucose levels. Which hormone is likely to be found in highest concentration in her blood? ---Patient A has high blood glucose. The body's hormonal reaction to this condition will be to attempt to re-establish homeostasis. High blood glucose levels stimulate the cells of the pancreas to secrete insulin. Insulin stimulates cells to import glucose, decreasing blood glucose levels. This would return the blood toward homeostasis and therefore insulin is expected in high levels. Patient B has low blood glucose levels. Which hormone is likely to be in highest concentration in his blood? ---Patient B has low blood glucose levels. Glucagon—also secreted by the pancreas—stimulates the liver to breakdown glycogen to release glucose into the blood. In this case, more glucose would be necessary to reach homeostasis and therefore high glucagon levels would be expected.
blood pressure vs. blood vessel type
How does Q=AV and bernoulli's equation apply here?
cross-sectional area vs. blood vessel type (aorta/arteries/arterioles/capillaries/venules/veins/vena cava)
How does Q=AV and bernoulli's equation apply here?
velocity vs. blood vessel type
How does Q=AV and bernoulli's equation apply here?
Non-Mendelian Inheritance Patterns
Human genetics is usually far more complex than the simple dominant-recessive inheritance patterns discovered by Mendel Occasionally, MCAT questions will even feature examples that are known to NOT follow Mendelian patterns, but the question stem will include a note that you should assume dominant-recessive inheritance.
Human Taxonomy: Family
Human- Family: Hominidae The rest of the taxa for humans, Homonidae, Homo, and Homo sapiens are just increasingly specific classifications for human or very "human-like" creatures— such as Neanderthals, Homo erectus, etc
Human Taxonomy: Genus
Human- Genus: Homo The rest of the taxa for humans, Homonidae, Homo, and Homo sapiens are just increasingly specific classifications for human or very "human-like" creatures— such as Neanderthals, Homo erectus, etc
Human Taxonomy: Order
Human: Order: Primates Primates are essentially all of the apes, gorillas, monkeys, and humans. Common distinguishing characteristics include opposable thumbs, fingernails, and an enlarged cerebral cortex
Human Taxonomy: Class
Humans- CLass: mammalia Mammals are warm-blooded vertebrates that usually give live-birth to their young, have hair or fur, and mammary glands
Human Taxonomy: Species
Humans- Species: Homo sapiens The rest of the taxa for humans, Homonidae, Homo, and Homo sapiens are just increasingly specific classifications for human or very "human-like" creatures— such as Neanderthals, Homo erectus, etc
Human Taxonomy: Kingdom
Humans-Kingdom: Animalia Animals are multicellular, motile, heterotrophic eukaryotes. They are distinguished from plants, algae, and fungi by not having cell walls
Innate Immunity
Immunity that is present before exposure and effective from birth. Responds to a broad range of pathogens. The body's non-specific attack of pathogens. All forms of innate immunity are present at birth, NOT acquired in any way. Includes all immune responses that are NOT specific to one particular virus, bacteria, pathogen, etc. Examples include: skin, stomach acid, enzymes in the mucus and saliva, digestive enzymes, blood chemicals, fevers, inflammation, and non-specific phagocytosis.
Describe how the mass of DNA differs for each of the above scenarios.
In a human diploid cell, prior to S phase, there are 46 unreplicated chromosomes, 23 of which originated from the father and 23 of which originated from the mother. These unreplicated chromosomes do not contain sister chromosomes. Let's define these unreplicated chromosomes as having a mass of m. After replication, there are 46 dyads, or duplicated chromosomes. A dyad features two identical sister chromatids attached to the same centromere. The mass of a dyad would be 2m. Therefore, during DNA synthesis the mass changes from m to 2m, but the number of chromosomes does NOT change. In a human diploid cell, the chromosome number will always be 2n, but the mass could be m or 2m depending on whether or not S-phase has occurred. A tetrad is the set of two dyads aligned atthe metaphase plate during Meiosis I, which are physically adjoined to one another by at least one DNA crossover. A human gamete, which is haploid, would have a mass of 0.5m. . The take home point is that the chromosome number does NOT change when DNA is replicated, you just end up with twice as much DNA per chromosome. The only time the chromosome number changes is during Meiosis I, or after the fusion of gametes in the production of a zygote
Thin filament
In skeletal and cardiac muscle tissue, a filament composed of actin, tropomyosin, and troponin. Thin filaments are attached to teh Z lines of the sarcomers and slide over thick filaments during muscle contraction. Microfilaments and polymers of the protein actin. Feature tropnin and tropomyosin, which tropomyosin stops myosin binding heads from attaching.
non-Mendelian inheritance patterns: Incomplete Dominance
Incomplete Dominance is an expression pattern in which the phenotypes of the dominant and recessive alleles appear to be mixed or blended in the phenotype of a heterozygote. For example, RR may give red flowers, rr white flowers, but Rr gives pink flowers (rather than the normal dominant-recessive pattern wherein Rr would still produce red flowers).
non-Mendelian inheritance patterns: Incomplete penetrance
Incomplete Penetrance occurs when various individuals all have identical genotypes and yet some have the disease phenotype and others do not
Uncompetitive Inhibitior
Inhibitor binds ONLY with the enzyme-substrate complex. Binding to ES to form ESI to prevent enzyme from reacting with substrate to form product ---E+s -> ES +I-> ESI Vmax = DECREASES - As Vmax decreases, Y intercept increases Km = DECREASES - As Km decreases, X intercept increases, thus it gets more negative - the inhibitor binds the enzyme only after the enzyme-substrate complex is formed and does not bind the active site. If the inhibitor can bind only after the enzyme-substrate complex forms (but must act before substrate is converted to product), then depending on the rate of the enzyme, the time window for inhibitor action is very limited. Example- Lithium, a drug used to treat manic depression, has been shown to act as an un-competitive inhibitor in the phosphoinositide synthesis pathway, inhibiting inositol monophosphatase and thus preventing inositol recycling in the brain.
Competitive Inhibitior
Inhibitor binds at the active site; The inhibitor resembles the substrate in shape; the inhibitory effect can be overcome by increasing the concentration of the substrate. Vmax = NO CHANGE Km = INCREASES the inhibitor resembles the substrate and fits into the active site reversibly, competing for active site occupancy with the substrate. An example of competitive inhibition is statin drugs.These drugs are HMG-CoA reductase inhibitors used to lower cholesterol levels by inhibiting the enzyme's function of producing cholesterol in the liver. The statin drugs inhibit HMG-CoA reductase by occupying the enzyme's active site, prohibiting HMG-CoA to enter and preventing the enzyme from converting HMG-CoA to mevalonic acid, which is an irreversible step in the cholesterol synthesis pathway. Because statins bind the active site reversibly, they are competitive inhibitors and not irreversible inhibitors.
IRREVERSIBLE INHIBITION
Inhibitor binds covalently to the enzyme and/or the active site, disabling the enzyme for either a prolonged period of time, or permanently. alters the enzyme in such a way that the active site is unavailable for a prolonged duration or permanently; new enzyme molecules must be synthesized for the reaction to occur again Aspirin is an example of irreversible inhibition. It binds the active sites of cyclooxygenase 1 and 2 irreversibly to prevent their inflammatory responses
Mixed Inhibitor
Inhibitor has unequal affinity for the E-S and the E, favoring one over the other. the inhibitor can bind the enzyme whether or not the substrate is bound, but has a preference for one state over the other. This means it is a mix of non-competitive and uncompetitive inhibition. Example- The metal palladium is a mixed inhibitor for xanthine oxidase, an enzyme that converts xanthine to uric acid. -Vmax = DECREASES --- Vmax decreases, Y intercept increases - Km = DECREASES if inhibitor = ^affinity for E-S over E ---If Km decreases, X intercept increases - Km = INCREASES if inhibitor = ^affinity for E over E-S ---If Km increases, X intercept decreases
Secondary Protein Structure
Interactions of the peptide back bone Alpha Helices- Hydrogen bonding between carbonyl oxygens and amide hydrogens are exactly 4 residues apart, including residues involved in H bonding Each amino acid forms a Hydrogen bond with the 4th amino acid following in in chain R Groups are directed AWAY from the alpha helix cylinder (perpendicular) Beta Sheets: Hydrogen BOnding Between ALL of the carbonyl oxygens in one row and the amide hydrogens --- all residues involve hydrogen bonding ---R groups are directed perpedicular to the plane of the beta sheet, on both sides --- Beta sheets assume a pleated conformation, due for the need for carboxyl and amide groups to line up properly to allow hydrogen bonding Proline is usually the FIRST residue at the very end of the Alpha Helix. Keratin- Found in hair and nails- alpha helices Fibrin- MOlecules that make up silk- beta sheets
Cardiac Muscle
Involuntary, striated only one nucleus Contraction: Cardiac muscles contain sarcomeres similar to skeletal muscles, use same sliding fialment mechanism Important Feature: --- Like skeletal muscle, it utilized myoglobin and has a large number of mitochondria to prevent fatigue --- Cardiac muscle cells/fibers are connected by intercalated discs containing gap junctions --- These junctions allow ions to pass and initiate action potential --- Cardiac cells continue dividing after differentiation unlike muscle cells Autorhythmic- ---The SA node acts like a natural pacemaker for the heart. The action potential for each heart beat originates in the SA node, not with a signal from the nervous system. ---Nerves do innervate the heart, but they only regulate its rhythm up or down—they do not initiate that rhythm. ---The vagus nerve (parasympathetic) slows the heart rate, and sympathetic nerves increase heart rate
Arrival of Action Potential
Junction between a skeletal muscle and a somatic motor neuron is called the neuromuscular junction Acteylcholine (ACh) is the ONLY neurotransmitter used at neuromuscular junctions When Ach is released from the motor neuron at the NM junction, action potential is initiated The action potential spreads along the muscle cell sarcolemma and down specialized invaginations of the sarcolemma called T-tubules, which go into the muscle cell T tubules interface directly with the sarcoplasmic reticulum, similar to the ER found in muscle cells At this point, the electrical impulse spreads from the T-tubules to the SR, stimulation SR to release Ca2+ Ca2+ initiates muscle contraction, and only occurs when Calcium is present. When contraction is finished, Ca2+ is transported back into SR untill next contraction, and this is done through active transport.
Major Non-enzymatic Protein Functions
Keep it simple and recognize proteins The central dogma is certainly important, as are enzymes, but students often miss questions when they fail to recognize proteins in other circumstances. Many MCAT-2015 questions reward the examinee for a simple recognition such as this: STEM = "In what part of the cell is calmodulin synthesized?" The unsophisticated student will think this requires specific prior knowledge about the biochemistry of calmodulin. All it really requires is recognizing that calmodulin is a protein. Remember that ANY protein in the cell must have been coded for by DNA. Alternate splicing and post-transcriptional processing allows for a greater variety of proteins, but ultimately all proteins are still gene products.
Michaelis-Menten Saturation Curve
M-M Saturation Curve: A graph of reaction velocity vs. substrate concentration [S]. This graph reveals the relationship between ½vmax and Km, as well as the overall concept of "saturation kinetics." Saturation Kinetics- Vmax is the rate of the reaction at saturation levels of substrate. This is the theoretical maximum rate of the reaction At low substrate concentrations, the rate of the reaction increases quickly. As more and more substrate is added, the rate increase slows down. This is because at low substrate concentrations, there is a much higher chance of free substrate encountering an empty enzyme active site, but as substrate concentration increases, that likelihood continuously decreases. At max saturation, the velocity will hold steady, as the enzyme molecules in the reaction are always occupied with a substrate molecule (as soon as a substrate molecule is converted to product, a new substrate molecule is picked up). Km is the Michaelis constant, the substrate concentration at half Vmax. This constant is used in calculations in Michaelis-Menten kinetics, to calculate the rate of a reaction at a given concentration of substrate using the equation: v= (Vmax [S])/(Km + [S]) In general, if you have a very high Km value, the binding affinity is small. A low Km means binding is strong. Don't memorize here... realize if Km is small, that means that it requires less substrate to get the enzyme to do it's thing. The enzyme loves it, and it binds tightly. A high Km value means you need a lot of substrate to get the enzyme to act on it. Enzyme feels kinda meh about the substrate in this case.
Fungal Reproduction
Majority of life as a haploid, meaning they have half the number of chromosomes as diploid a only contains one set of complete chromosomes, which is a result of meiosis. They have like, intertwining branches called hyphae Yeasts reproduce by budding Most fungi have sexual and asexual reproduction, sexual happening when there is stress or a bad environment or asexual when life is good. Sexual reproduction is costly in terms of energy, but increases genetic diversity. Asexual reproduction is less expensive than sexual reproduction in terms of energy, but provides no genetic diversity. When fungi experience difficult survival conditions they can employ sexual reproduction so that future generations have an opportunity to adapt/evolve. When survival is easy and resources are plentiful, the fungi can simply save the energy and employ asexual reproduction because adaptation is not necessary.
Meiosis
Meiosis Yields Four (4) genetically distinct, haploid daughter cells! Centromeres do NOT split during meiosis I, but do split during meiosis II. Cells in mitosis would have 2n chromosomes and cells in meiosis II would have only n chromosomes. In other words, unless you can count the chromosomes (the one exception mentioned above), diagrams of mitosis and meiosis II are indistinguishable. To distinguish between mitosis and meiosis I, there a couple of items to look for. First, if there are tetrads depicted (two pairs of sisters; four chromatids forming a single unit during crossing over), then the cell must be in meiosis I. During mitosis, the chromosomes would be condensed, but you would see only dyads. There would be no tetrads. Tetrads never form during mitosis. The next key difference occurs during metaphase. During metaphase of mitosis the replicated chromosomes (dyads) line up single-file at the metaphase plate. By contrast, during metaphase of meiosis I the chromosomes are NOT lined up single-file, they line up side-by-side as pairs of homologues, or tetrads. Seeing tetrads is a dead giveaway that you are looking at a depiction of meiosis I. It can also be helpful to consider the centromeres. When looking at metaphase of mitosis you should see a single-file line of centromeres aligned along the metaphase plate. When looking at meiosis I, you should see two side-by-side centromeres, one centromere for each of the two chromosomes forming the tetrad. During anaphase, the centromeres split. In mitosis, the sister chromatids are separated to opposite poles, but in meiosis I the two homologues that make up the tetrad are separated to opposite poles. Thus, during anaphase of mitosis you should see single chromatids being pulled to opposite poles of the cell, but in meiosis I you should see dyads being pulled to opposite poles of the cell
Mitosis vs Binary Fission
Mitosis is a complex process coordinated and heavily regulated by a large number of genes and involving intricate interactions between centrioles, spindle fibers (microtubules), centromeres, chromosomes, and many other cellular components. Absent any errors, mitosis delivers an exact and equal amount of DNA to each new daughter cell. Binary fission is the method employed by prokaryotes and involves none of the items listed above, except for DNA. In binary fission, the circular DNA is copied and attached to the membrane. The cell splits, pulling the two copies apart, and each daughter cell gets one copy of the chromosome. An important caveat, however, is that prokaryotes contain extrachromosomal DNA (usually circular plasmids). There is no system for segregating this DNA, so each daughter cell may or may not get certain plasmids based solely on random chance.
Seminal Vesciles
Most of the semen, fructose and prostaglandins are formed in the (prostate/seminal vesicles).
Dyneins
Move along microtubules from (+) to (—) end [periphery to center of the cell; nerve cell dendrite -> cell body] Carry cargo back towards the cell body
Kinesins
Move along microtubules from (—) to (+) end [center of cell to periphery; nerve cell body -> dendrite] It is moving proteins toward the outside.... they carry large cargo from one part of the cell to another, walking on the microtubles, that act as a high way. THus why microtubules assist in moving things in the cell.
Motor Proteins
Myosin ( power stroke, cellular transport Kinesins and Dyneins (Vesicles, cellular transport, cell devision, cilia, flagella)
The Sliding Filament Mechanism
Myosin filaments are a bundle of individual myosin molecules Each one features a globular myosin which binds to the actin filaments to form a myosin cross bridge, responsible for the actual contractile mechanism this is important: The DEFAULT, LOW-ENERGY position for the myosin heads is bent. Between contractions, ATP hydroylysis (ATP-> ADP + Pi) provides energy to straigte/cock these myosin heads into high energy, straight position. After calcium is released, allowing tropomyson to move and all myosin heads to bind to actin, these heads release ADP and Pi This is essentially pulling the trigger to allow the heads to relax back to default, bent position, dragging the actgin filametns with them--- this is the power stroke After the power stroke, ATP binds to the myosin head again to release the actin filament Tropomyosin rebinds to the site The attached ATP is hydrolyzed to provide the energy to push the head back into high-energy/ straight or cocked position, ready for another contraction cycle ---ATP releases myosin head from the actin binding site, 2nd it must be hydrolyzed to move the myosin from their relaxed bent position to their high energy straight position. IF NO ATP IS PRESENT, myosin heads cannot detach, and it is stuck in contraction position/ rigor mortis If no Ca2+ is present, we do NOT get rigor, but the inability to contract (flaccidity
Secondary Messenger System
NT binds outside the cell to activate adenylate cyclase (enzyme complex), splits ATP to make cyclic AMP, sets up a cascade, activates enzymes that can stimulate change in gene expression usually occurs via a cascade. In a cascade, one hormone activates another hormone, enzyme, or other signaling molecule. The signal recipient then activates another member of the cascade, with the size of the reaction and the number of molecules involved increasing with each step.
FSH
Name: FSH Peptide/Water soluble Function: Stimulates growth of follicle (oocyte/egg) during menstrual cycle and production of sperm Organ that secretes it: Anterior Pituitary Where the endocrine organ is located:
Glucagon
Name: Glucagon Peptide/Water soluble Function: A hormone secreted by the pancreatic alpha cells that increases blood glucose concentration Organ that secretes it: Pancreas Where the endocrine organ is located: Close to stomach, posterior side
hCH
Name: Human Chorionic GOnadotropin Peptide/Water soluble Function: Prevents degeneration of corpus luteum, maintaing pregnancy Organ that secretes it: embryo/placenta Where the endocrine organ is located: egg/placenta
hGH
Name: Human Growth Hormone Peptide/Water soluble Function: Stimulates growth throughout the body Organ that secretes it: Anterior Pituitary Where the endocrine organ is located: brain
Insulin
Name: Insulin Peptide/Water soluble Function: Hormone released by the pancreas that lowers blood sugar Organ that secretes it: Pancreas Where the endocrine organ is located:
LH
Name: LH Peptide/Water soluble Function: Surge causes ovulation, stimulates secretion of sex hormones estrogen and testosterone Organ that secretes it: Anterior Pituitary Where the endocrine organ is located: Head
Oxytocin
Name: Oxytocin Peptide/Water soluble Function: Stimulates contractionsduring childbirth and milk secretion during nursing Organ that secretes it: Posterior Pituitary Where the endocrine organ is located: brain
PTH
Name: Parathyroid Hormone Peptide/Water Soluble Function: increases blood calcium by stimulating proliferation of osteoclasts, uptake of Ca2+ in the gut, and reabsorption of Ca2+ in the kidney Organ that secretes it: Parathyroid Where the endocrine organ is located: Throat
Prolactin
Name: Prolactin Peptide/Water soluble Function: Stimulats Milk Production in the breasts Organ that secretes it: Anterior Pituitary Where the endocrine organ is located: brain
Neutrophils
Neutrophils are one of three kinds of granulocytes—the other two being basophils and eosinophils. The three cells get their names from how they appear when stained and viewed under a light microscope. Commonly used laboratory preparations stain basophils a dark blue (due to the basic nature of the granules), eosinophils a bright red (due to the acidic nature of the granules), and neutrophils a "neutral" pale pink. Similarly, the term "granulocyte" comes from the fact that all three cells contain large cellular granules easily visible with a microscope. Neutrophils are phagocytes that are recruited to areas of infection and inflammation by chemotaxis. They live for only about 5 days, but are the most abundant of all white blood cells. The pus created at a wound is mostly dead neutrophils.
Prosthetic Groups
Non-protein species that ARE permanently attached to the enzyme and are required by the enzyme to function. tightly bound cofactors or coenzymes that are necessary for enzyme function example- The mechanism of action of the pyruvate dehydrogenase complex (PDC) relies on the use of three prosthetic groups in the enzyme active site. Think of the heme group on hemoglobin...
Fatty Acid Synthesis
Occurs in Cytosol of liver cells Fatty Acid Syntheis is always construction of a 16 C palmitic Acid --- Only FA human body can syntehsize from scratch Other forms of lipid synthesis like phospolipids and steroids, happens on Smooth ER Source of Acetyl-CoA comes form Citrate shuttle because Acetyl CoA groups can't pass through inner mitochondrial membrane, so it funnels atty acids from the mitochondria to the cytosol using this shuttle
Obesity and Regulation of Body Mass:
Occurs through hormones, food intake, and activity level Main hormones are leptin, ghrelin, orexin --- Leptin- A satiety hormone, regulates energy balance by inhibiting hunger, opposed by ghrelin, which is the hunger hormone Threshold for weight gain is lower than weight loss Healthy individuals burn carbs first, then fats, then proteins How many calories are in one gram of a) fat, b) protein, c) carbohydrate? a) 9 kcal/g, b) 4 kcal/g, c) 4 kcal/g.
Chymotrypsin
One of the main pancreatic proteases; it is activated (from chymotrypsinogen) by trypsin. proteases that cleave peptide bonds at specific amino acid sequence a digestive enzyme component of pancreatic juice acting in the duodenum where it performs proteolysis, the breakdown of proteins and polypeptides. Chymotrypsin preferentially cleaves peptide amide bonds where the carboxyl side of the amide bond (the P1 position) is a large hydrophobic amino acid (tyrosine, tryptophan, and phenylalanine)
Electron Transport Train
Oxidative Phosporylation occurs at ATP synthase, combing ADP and Pi to generate ATP through proton gradient Via NADH: In total, from the NADH molecule, 10 protons are pumped through this order Complex I pumps 4 Protons Complex II pumps 0 Protons Complex III pumps 4 protons Complex IV pumps 2 protons Every NADH produces 3 ATPS Via FADH2 results in 6 protons pumped: Complex II pumps 0 Complex III pumps 4 Complex IV pumps 2 To generate one ATP molecule, 3 protons are used Every FADH2 produces 2 ATPs
Mendelian Genetics: P1 Generation
P1 Generation is the first parental generation in Mendel's experiments. Both parents in this generation were pure-breeding (i.e., homozygous) for their trait. This would tell us that one was homozygous dominant (TT) and the other homozygous recessive (tt).
Polymerase Chain Reaction (PCR)
PCR requires that one know at the outset the specific sequence on the DNA that will be used. Primers are then synthesized that will anneal with the DNA on either side of the target sequence. Two primers are required: one that is complimentary to the 3' end of the sense strand and one complimentary to the 3' end of the antisense strand. The DNA is heated to about 95° C to denature the helix and the primers to denature the helix. The primers are added along with special DNA polymerases (usually Taq Polymerase) harvested from thermophilic bacteria that live in hot springs. The mixture is then cooled to a much lower temperature to allow the primers to anneal (50-65°C). The temperature is then raised again to the optimum temperature range for the thermophilic enzyme (around 72° for Taq Polymerase). The polymerase then copies the DNA, creating two new DNA helices. The temperature is raised again high enough to denature both helices and the entire process is repeated. The number of copies doubles for each cycle.
Citrate-Acetyl-CoA Shuttle
PROBLEM: During periods of energy abundance, Acetyl-CoA groups in the mitochondria are redirected from the Citric Acid Cycle to fatty acid synthesis. However, fatty acid synthesis occurs in the cytosol and Acetyl-CoA cannot pass through the inner mitochondrial membrane. SOLUTION: Acetyl-CoA is combined with OAA to form citrate (normal first step of Citric Acid Cycle). Citrate is able to pass through the membrane, and is them converted back to OAA and Acetyl-CoA in the cytosol.
Carnitine Shuttle
PROBLEM: Fatty acids cannot pass through the inner mitochondrial membrane, where they need to be in order to go through beta-oxidation. SOLUTION: The enzyme Carnitine acyltransferase attaches the fatty acyl group from an acyl-CoA to the hydroxyl group of carnitine. A translocase enzyme on the inner mitochondrial membrane moves one acyl-carnitine into the matrix and one carnitine back out.
Glycerol-3-Phosphate shuttle
PROBLEM: NADH cannot enter the mitochondria to participate in the ETC. • Think of this as a second solution to the same problem, but a minor contributor. The MalateAspartate Shuttle is the major contributor and the Glycerol-Phosphate Shuttle helps out. SOLUTION: NADH donates two electrons to dihydroxyacetone phosphate (DHAP) to form Glycerol-3-Phosphate (G3P). G3P is converted back into DHAP by Mitochondrial G3P dehydrogenase, an enzyme bound to the cytosolic surface of the inner mitochondrial membrane. The enzyme passes the electrons to FAD to form FADH2 and skips complex 2 to go directly to complex III.
Malate-Aspartate Shuttle
PROBLEM: NADH cannot pass through the inner mitochondrial membrane. Therefore, NADH produced from glycolysis cannot enter the ETC without the help of this shuttle. SOLUTION: NADH donates two electrons to oxaloacetate (OAA) converting it to malate. Malate passes into the matrix via the MALATE-Alpha-KETOGLUTARATE ANTIPORTER. ---Inside the matrix, malate is converted back into OAA, regenerating NADH. OAA is then converted into aspartate so that it can be pumped back into the cytosol via the GULATAMATE-ASPARTATE SHUTTLE.
Peptide Hormones
Peptide hormones are water soluble and dissolve in the blood readily. peptide hormones, by contrast, act at a variety of cell locations. Peptide hormones are hydrophilic and cannot dissolve through the membrane, thus they require a membrane receptor. This goes through the secondary messenger system! always
Bone
Physical support and movement, protection of vital structures, mineral storage and regulation of blood mineral concentration, and blood cell formation. Osteocytes: Mature bone cells surrounded by a mineral matrix. Osteoclasts: Bone cells that break down and resorb bone matrix, releasing the component minerals (Ca2+ and P) back into the blood. Osteoblasts: Immature bone cells that secrete collagen, organic compounds, and minerals forming a bone matrix around themselves. Once they are completely enclosed by matrix, they differentiate into osteocytes. Calcatonin stimulautes Ostoblast, storing more Ca+ in the bones, When blood levels are above normal, calcitonin inhibits osteoclast activity. Osteoblast activity continues and thereby a net increase in bone structure results. The calcium used by osteoblasts to build new bone matrix comes from the blood and therefore blood calcium levels decrease PTH stimulates osteoclasts, breaks down bones for Ca2+, As a result, blood calcium levels rise. The two hormones also have predictable effects on the absorption of calcium at the gut and the reabsorption of calcium in the kidney.
Apoptosis
Programmed cell death featuring autolysis of cell contents by lysosomes. Initiated in cells exposed to extreme heat, radiation, viral infection, DNA damage, etc. or to remove healthy but unwanted cells (e.g., interdigital tissues during embryological development of the fingers).
Prokaryotes vs Eukaryotes
Prokaryotes: -have no nuclei, -no membrane-bound organelles, -no histones -no chromosome structure; -they do have circular DNA and 70S (30S and 50S) ribosomes. Eukaryotes: -True Nucleus -Complex -Membrane bound organelles -linear DNA with histones -Chromosome structure - 80S (60S & 40S) ribosomes ribosome measures do not add up (i.e., 50S + 30S ≠ 70S) because they are not directly related to mass or volume, but are sedimentation coefficients derived from the result of centrifuging the ribosomes
Conjugated Protein
Protein associated with factors, covalently or intermolecular attracted Hemoglobin is an example of a conjugated protein dud to it's non-protein heme group. HOLOENZYME- A conjugated protein with an enzyme and cofactors examples of conjugated proteins are lipoproteins, glycoproteins, phosphoproteins, hemoproteins, flavoproteins, metalloproteins, phytochromes, cytochromes, opsins and chromoproteins: they all have cofactors bounded one way or another
Simple Proteins
Proteins that contains only amino acids NO non-protein cofactor or prosthetic If it is a simple protein that is an enzyme, it is called an apoenzyme. APOENZYME- SIMPLE PROTEIN examples of simple proteins are histones, globulins, glutelins, albuminoids and albumins. When these proteins are broken down chemically with water via the process of hydrolysis, they usually break down into only amino acids
ΔG = ΔG°' + RTlnQ
R= Universal Gas Law Constant T is temperature Q is the rxn quotient ΔG°' is a fixed, unchangeable value, while ΔG can vary. --- ΔG°' is predetermined for any given rxn according to specific standardized criteria ---ΔG°' represents the free energy associated with proceeding from a standard state concentration (1M of each reactant) to equilibrium --- When ΔG= 0, there is no driving force in either direction...
Peptide Bond Formation
Reaction Type: Dehydration Syntehsis and Acyl Substitution done with 1' amine groups The amine group nitrogen (nucleophile) from the NEW amino acid ATTACKS the carbonyl carbon (electrophile) on the C-TERMINUS, of the growing peptide chain Peptides are Written, Read, and Synthesized form N-Terminus -> C-Terminus Resonance beween pi electrons on the C=O bond and the Nitrogen lone pair on the C-N bond, yields 2 resonance structures for any peptide bond, thus the actual structure i the hybrid of the two. So the C=O bond and C-N bond in a peptide bond have double bond character Double Bond character-> RIGID peptide bond with LIMITED rotation
The Dynamic Steady State
Refers to the ability of living things to maintain a constant, steady internal environment that is not NOT in equilibrium with its surroundings Our body sustains a different temperature than the room or our body continues to stay in an organized state while the parts in our environment continues to decay Remember that equilibrium is different from the steady state: Equilibirum is a dynamic state that only exists at the lowest possible entropy and energy for that system, if we were in equilibrium with our surroundings, we would be dead. Our body is constantly using energy to maintain a homeostatic state away from equilibrium Essentially, our bodies are a closed system
Gluconeogensis
Reversal of glycolysis to make glucose from pyruvate 3 glycolytic enzymes are substituted for 3 unique enzyme specific to gluconeogensis -Pyruvate carboxylase, PEP carboxykinase, Fructose 1,6 Biphosphatase, GLucose 6-Phosphatase, all are phosphorylation reactions and are irreversible Always refer to the liver when gluconeogensis is referred to, it is fasting and needs to increase blood sugar
Stereochemistry of Carbohydrates
Review Absolute configuration, Epimers, Anomers R/S does not equal D-/L-, --R/S is based on chiral carbons in general --D-/L- is specific for sugars D-Sugars= ALl human sugars, L-Sugars not natural to human
Desmosomes
STrongest of cellular junctions, weld cells together protect against stress not watertight Join two cells at a single point, attach directly to the cytoskeleton of each cell. Found in tissues that normally experience a lot of stress due to sliding. occur in tissues subject to shear stress such as the epidermis. They are particularly common in stratified epithelium. An autoimmune disease that produces antibodies against the desmosome protein (desmoglein) leads to separation of skin layers and large, painful blisters
The Mouth
Saliva provides lubrication and amylase, 1st enzyme food is exposed to. Digestion begins in the mouth with physical digestion of all food types and chemical digestion of carbohydrates via alpha- amylase. --- This reaction is called hydrolysis, it breaks the carbohydrate bonds via hydrolysis
Western Blot
Same basic procedure and concepts as Northern and Southern blots; used on proteins segments instead of nucleotide segments. The probes used are radiolabeled antibodies rather than nucleotide sequences.
Parietal Cells
Secrete HCl into gastric pits/stomach lumen HCl is responsible for the extreme acidity (pH=2) of the stomach It is the extreme acidity that converts pepsinogen to pepsin for active form on enzyme
Prostate Gland
Secretes fluid to that mixes with seminal fluid -> semen
Intracrine
Signal molecules (usually steroids) bind to receptors inside the same cell that produced them, without ever being secreted outside of the cell.
Autocrine
Signal molecules secreted by a cell bind to receptors on that same cell.
Paracrine
Signal molecules secreted by one cell bind to receptors on other cells in the local area. Neurotransmitters acting in the synaptic gap are an example of a paracrine response.
Juxtacrine
Signaling requires direct contact between two cells Example of this is the t cell and b cell relationship, Help t cell is activating the b cells directly through direct contact
Biochemical Shuttles:
Shuttles that transport molecules across permeable membranes Some cases, the molecule is activated by adding a functional group that increases solubility Others, only a portion of the membrane impermeable parent molecule is passed through the membrane sometimes e- are passed through the membrane and the parent stays outside Some shuttles do NOT require enrgy inptu while others do When energy is required, it decreases the net energy value for oxidation of shuttled molecule Malate-Aspartate Shuttle, Glycerol-3-Phosphate shuttle, Carnitine Shuttle, Citrate-Acetyl-CoA Shuttle
B-Cells Antigen Presentation
Specialized immune cells that bind their specific antigen, engulf it via receptor-mediated endocytosis, and present the antigen on MHC proteins on their cell membranes. Helper T-cells recognize and bind these antigens, which causes the helper T-cell to release chemicals that stimulate other B and T cells. Most importantly, the helper T-cells stimulate the original B-cell to divide into a plasma cell and a memory B cell as described above. In other words, it is through antigen presentation that a Helper T-cell "helps" (i.e., activates) a B-cell to perform its function. A B-cell can either bind to a free-floating antigen, or it may have an antigen "presented" to it by a macrophage.
Centrioles/Centrosome
The centrosome is an amorphous area of proteins and nucleating factors within which the centrioles are located It organizes microtubules, flagella, and cilia; it also plays a key role in cell division.
Testosterone
Steroid Function: stimulates development of secondary sex characteristics and closing of epiphyseal plates Organ that secretes it: Gonads (Testes)
Estrogen
Steroid Function: stimulates female sex organs; causes LH surge in menstruation Organ that secretes it: gonads (ovaries)
Progesterone
Steroid Function: stimulates growth and maintenance of uterus during pregnancy Organ that secretes it: GOnads (ovaries)
Gallbladder
Stores and Concentrates bile, but does NOT PRODUCE BILE, it's the liver that produces bile Bile emulsifies fats, separates fat molecules from each other to increase the surface area available for enzymatic digestion This is a physicall digestion, cause it doesn't break any bonds
Lacteal
Structures within the villi that line the small intestine and that absorb fatty acids and glycerol into the lymphatic system.
Substrate-Enzyme Specificity
Substrate: --a molecule that is acted upon by an enzyme. A substrate could be a small molecule, a protein, a lipid, DNA, etc. The key here is that a substrate is a molecule that is converted to a product by an enzyme. Active Site: --part of an enzyme where the substrate is converted to product. It is typically a small port or pocket that will hold only that enzyme's highly-specific substrate --Amino acids are specific and there are specific properities between substrate and rxn being catalyzed, thus a conformation can occur Enzyme-Substrate Complex: formed when the substrate is bound in the active site. Once the enzyme-substrate complex is formed, the substrate will be converted to product (going through the transition state first). This is represented by the basic kinetics formula: E + S ↔ ES -> EP ↔ E + P
Sympathetic vs Parasympathetic
Sympathetic: "Fight or Flight." -Cell bodies located far from the effectors. It has shorter myelinated axons -Neurotransmitters: acetylcholine at the ganglia, norepinephrine at the effector. Some examples of sympathetic response is that it will cause the increased herat rate, blood pressure, blood flow to skeletal muscle, flow to the brain, and decreases flow to the skin. Eye dilation. Sympathetic has shorter myelinated axons Parasympathetic: "Rest and Digest." -Cell bodies located very close to, or inside, the effector. It has longer myelinated axons. -Neurotransmitters: acetylcholine only, at both the ganglia and the effector. Examples- Increased blood flow to digestive system, blood flow to skin. It usually works in oppisote sympathetic. Pupil constriction is parasympathetic
Cell-Mediated Immunity
T-Cell Immunity involves the activation of phagocytes, antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen. T-cell mediated immunity or T-cell immunity : activating antigen-specific cytotoxic T cells that are able to induce apoptosis in body cells displaying epitopes of foreign antigen on their surface, such as virus-infected cells, cells with intracellular bacteria, and cancer cells displaying tumor antigens; type of immunity produced by T cells that attack infected or abnormal body cells T-Cells= Cell-mediated immunity T-cells are made in the bone marrow, but mature in thymus T cells have receptor proteins embedded in their cell membrane Unlike B-Cells, they never produce free antibodies They are tested in the thymus against the host's own membrane proteins (self-antigens) All T-Cells matching a self-rpotein are destroyed, leaving only cells that will recognize invaders T-Cells that pass this test will differentiate into different T-Cell types CELL-MEDIATED= SELF-ATTACK OF DISEASED CELLS, When the body finds that one of its antibodies recognizes "self," that antibody is suppressed. You should know that some self-attack, at low, controlled levels is actually desirable to destroy infected or damaged cells.
Mendelian Genetics: F1 Generation
The F1 Generation was the offspring from the P1 Generation, which Mendel crossed with each other. Both parents in the F1 generation had to be heterozygotes (Tt)
Mendelian Genetics: F2 Generation
The F2 Generation was the offspring of the F1 generation. The F2 generation showed the characteristic 3:1 phenotypic ratio and 1:2:1 genotypic ratio
Hemoglobin Binding Curve
The MCAT has demonstrated that they clearly expect prior knowledge of this curve as demonstrated by their asking stand-alone questions that cover these concepts without presenting an example of the curve or discussing it in a passage. It would be logical to expect future questions on all aspects of this curve, especially trends related to pH, carbon dioxide concentration, and temperature. One question asked previously about BPG, but some helpful information was given in the stem. Protons, CO2, allostericcly inhibits hemoglobin from getting oxygen. THe oppisote happens when more O2 binds, the easier it is to bind more. But when it is let go, the easier it is let go.
Residual Volume
The air that remains in the lungs after maximal expiration.
Primary Protein Structure
The amino acid sequence
Ascending loop of Henle
The ascending Loop of Henle carries the filtrate out of the medulla and back into the cortex. This portion of the loop is impermeable to water and actively transports ions out of the filtrate and into the medulla. This continuous "dumping" of salts into the medulla accounts for its hypertonicity. At the top of the ascending loop the filtrate is actually less concentrated due to the removal of these ions We use ATP to pump against the concentration gradient to get these ions like sodium back into the medulla
Mechanisms of Repair System: Base Excision
The base portion only is excised first via a DNA glycosylase; other enzymes then remove the sugar-phosphate backbone; then DNA polymerase and ligase replace the nucleotide.
CNS
The brain and spinal cord; interneurons only. No subdivisions.
Plasma Membrane
The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. The basic function of the cell membrane is to protect the cell from its surroundings. It consists of the lipid bilayer with embedded proteins.
Golgi Apparatus
The cellular "post-office" for proteins; organize, continue post-translational modification, excrete in vesicles bound for the plasma membrane, back to the ER, or to organelles.
Metaphase I
The centrioles are at opposite poles of the cell. The pairs of homologous chromosomes (the bivalents), now as tightly coiled and condensed as they will be in meiosis, become arranged on a plane equidistant from the poles called the metaphase plate
Distal Convoluted Tubule
The distal convoluted tubule (DCT) is the section of the nephron between the top of the ascending loop of Henle and the collecting duct. Recall that this segment passes directly by the opening to Bowman's capsule where the juxtaglomerular apparatus is located. The distal convoluted tubule regulates calcium, sodium and hydrogen concentrations—although for the MCAT we suggest you focus only on its sodium reabsorption function as regulated by the hormone Aldosterone. Recall that aldosterone stimulates increased sodium reabsorption at the DCT and the collecting duct. Less important, but worth remembering, is the fact that the DCT also reabsorbs calcium in response to parathyroid hormone (PTH). Between the loop of Henle and the collecting duct; Selective reabsorption and secretion occur here, most notably to regulate reabsorption of water and sodium
Anatomy of the Nephron
The functional unit of the kidney
Chromosomes
The major purpose of chromosomes is to efficiently package the very, very long DNA strands so they can easily be stored between divisions and moved during division.
The Small Intestine
The majority of all digestion and absorption occurs in the small intestine; digestion occurs primarily in the duodenum absorption primarily in the jejunum and ileum
Pathway of Digestive System
The most important roles of the mouth in digestion are to break up food into small pieces by chewing and to mix it with saliva, which contains the enzyme alpha-amylase and some specific classes of antibodies. The saliva lubricates the food, which aids its passage down the esophagus. Amylase initiates carbohydrate digestion. The pharynx ensures the bolus is delivered to the esophagus without entering the nasal cavities or the larynx, but no digestion of any kind occurs here and nothing is added to the bolus. The epiglottis is an upward-oriented cartilaginous flap that folds down over the opening to the larynx during swallowing to prevent food from entering the larynx. The esophagus utilizes peristalsis to push the bolus down and into the stomach. Peristalsis is the rhythmic contraction of smooth muscle in the wall of the gastrointestinal track that moves food forward. Once again, no digestion occurs in the esophagus and nothing is added. Food enters the stomach by passing through the cardiac sphincter, which is located at the junction of the esophagus and the stomach. The churning of the stomach continues physical digestion. The stomach is lined with gastric pits. Chief cells are one of four cell types lining these pits, which are, in turn, lined with four cell types. Chief cells, one of these cell types, release pepsinogen, a zymogen that will be converted to its active form, pepsin, by the low pH of the stomach lumen. Pepsin will hydrolyze proteins. Another of these cell types lining the gastric pits, the parietal cells, secrete the HCl that lowers the pH of the stomach to about 2. The partially digested food mix, now referred to as chyme, passes through the pyloric sphincter and into the upper portion of the small intestine, called the duodenum. The common bile duct and the pancreatic duct both release products into the duodenum. As a result, the duodenum receives bile from the liver and gallbladder, and, from the pancreas, a bicarbonate-rich solution and six digestive enzymes: trypsin and chymotrypsin digest protein, pancreatic amylase digests carbohydrates, lipase digests fats, and ribo- and deoxynuclease digest RNA and DNA. The bicarbonate ions are important because they raise the pH of the chyme to around 6—a necessary step because the enzymes just listed could not function at the much lower pH of the mixture arriving from the stomach. The chyme progresses through the small intestine to its middle section, the jejunum, and then to the final section, the ileum. There are no distinct boundaries marking these three sections. Most digestion occurs in the duodenum and most absorption (of food molecules, not water) occurs in the jejunum and ileum. The lining of the small intestine features finger-like projections called villi that increase the surface area for absorption. Individual epithelial cells along each villus have microvilli—long fingerlike projections of the cell membrane on their apical surface. Each villus' center is filled with blood vessels and a single lymph vessel called a lacteal. Fats are absorbed into the lacteal, NOT the blood vessels. Carbohydrates and proteins are absorbed into the blood vessels. The ileum empties into the large intestine on the right side of the abdomen (anatomical right) slightly above a blind (dead-end) pouch called the cecum. The appendix is attached to the cecum. The colon rises upward along the right wall of the abdomen (ascending colon), traverses across the abdomen (transverse colon) and then descends along the left wall (descending colon). The final segment of the colon is somewhat twisted and is therefore appropriately named the sigmoid colon. The primary function of the colon is the absorption of water and vitamins. The colon contains resident commensal bacteria that secrete vitamin K, thiamin, riboflavin, and vitamin B12. The rectum is the final segment of the large intestine. It connects to the anus and stores feces.
The Nervous System
The nervous system includes the brain, spinal cord, peripheral nerves, neural support cells (astrocytes, Schwann cells, ependymal cells, etc.) and sensory organs such as the eyes and ears. SENSORY MOTHER F-IN ORGANS
rRNA
The only enzyme The most abundant type of RNA, which together with proteins froms the structure of ribosomes. Ribosomes coordinate the sequential coupling of tRNA molecules to mRNA codons; also called ribosomal RNA. is the polymer of which ribosomes are constructed. Remind students that ribosomes are assembled in the nucleolus. Ribosomes are a non-protein entity that act as enzymes in the polymerization of proteins, and are an example of a non-protein enzyme
Depolarization
The opening of the voltagegated sodium channels causes a sudden spike in the membrane potential, from -70 mV tosomewhere around +40 mV . This process isreferred to as "depolarization
Hydrostatic and Osmotic Pressure
The osmotic pressure and hydrostatic pressures are opposing one another, depending on where they are coming from. The net filtration is what drives which way fluid flow is. These determine how much fluid leaves the capillary and how much is reabsorbed.
Stopping the Post-Synaptic signal
The post-synaptic membrane will be continuously stimulated as long as neurotransmitter is present. Specialized enzymes in the synaptic cleft must break down the neurotransmitter to interrupt its action. The most common one is acetylcholinesterase. The MCAT loves to ask about acetylcholinesterase. They often ask about acetylcholinesterase activators or inhibitors. Agonist is another term for an activator and antagonist is another term for an inhibitor.
Hyperpolarization
The potassium channels are somewhat slow to close as the membrane potential approaches -70 mV. Thus, the membrane potential actually dips to around -90 mV before gradually returning to the resting potential.
p^2 + 2pq + q^2 = 1 & p + q = 1
The terms p and q NEVER refer to a number or fraction of individuals—they do NOT refer to genotypes. p and q refer to the percentage of each allele present as a fraction of all of the alleles in the population. The term p^2 represents the fraction of individuals who have the homozygous dominant genotype (TT). The term q^2 represents the fraction of individuals with the homozygous recessive genotype (tt). The term 2pq represents the fraction of individuals with the heterozygous genotype (Tt). In other words, p and q represent the fractions of p and q alleles in the population. The terms q2, 2pq, and q2 all represent fractions of individuals with each possible genotype. All of the variables can be calculated simply by knowing that 90/1,000 individuals have a recessive phenotype. The fraction 90/1,000—by definition—is the term q2. Simplifying 90/1,000 we get 0.09. The square root of this is 0.3 and therefore q = 0.3. Because p + q = 1, p must equal 0.7. We can then calculate 2pg as: (2)(0.7)(0.3) = 0.42. To find p2 we simply square p: (.7)2 = 0.49. Therefore, 49% of the population have the genotype TT, 42% are Tt, and 9% are tt. From p and q we now that 70% of all alleles are p and 30% of all alleles are q.
Testicles
The testicles serve the primary functions of making, nurturing and storing sperm
Anaphase II
The third phase of meiosis II. During anaphase II the sister chromatids are finally spearated at their centromeres and puled to opposite sides of teh cell. Note that anaphase II is identical to mitotic anaphase, excep the number of chromosmes was reduced by half during meiosis I.
Tidal Volume
The tidal volume (TV) is the volume of air that enters and exits the lungs during an average, unforced respiration. Amount of air that moves in and out of the lungs during a normal breath
Menopause
The time of natural cessation of menstruation; also refers to the biological changes a woman experiences as her ability to reproduce declines. Know the general symptoms of menopause, including: hot flashes, vaginal dryness, and atrophy of breast tissue. All of these are the result of decreased estrogen and progesterone levels.
Vital Capacity
The total volume of air that can be exhaled after maximal inhalation. Vital capacity (VC) is the total volume of air the lungs can hold at maximum inflation, minus the residual volume
Main female reproductive organs
The vagina serves as the female copulatory organ, as the birth canal, and as an exit route for menstrual fluid. The cervix is the conical-shaped bottom portion of the uterus that projects into the rear, upper wall of the vaginal canal. It contains a small opening that allows for exchange of fluids, but must dilate significantly during child birth to allow for delivery. The uterus is an elastic, muscular pouch that receives a fertilized egg via implantation and provides nourishment for the developing fetus. Muscle contractions of the uterine wall, stimulated by oxytocin, facilitate the process of childbirth. The fallopian tubes are ducts that utilize ciliated epithelium to transport the egg from the ovary to the uterus. Fertilization usually occurs in one of the two fallopian tubes. The ovaries are the female gonads, homologous to the testes in males. The ovaries develop and release ova (i.e., eggs) on a regular 28-day cycle (on average). They also function as endocrine glands that secrete estrogen and progesterone.
Reserve VOlume
There are two reserve volumes, an inspiratory reserve volume (IRV) and an expiratory reserve volume (ERV). This is the volume of additional air that can be exhaled or inhaled after a normal, unforced expiration or inhalation.
Mitosis
There is no change in chromosome number during mitosis. Although the splitting of the centromere will separate a tetrad into two dyads, the total number has not changed. Diagrams used on the MCAT are usually highly schematic and designed so that the distinguishing features are as clear as possible. Mitosis Yields: Two (2) genetically identical, diploid daughter cells, which are also genetically identical to the mother cell that produced them. The centromeres split. A process of nuclear division in eukaryotic cells conventionally divided into five stages: prophase, prometaphase, metaphase, anaphase, and telophase. Mitosis conserves chromosome number by equally allocating replicated chromosomes to each of the daughter nuclei.
Bioenergetics
Thermodynamics of biological systems, refers to biochem being the chemistry of biological systems A reaction will be spontaneous if ΔG is less than 0, non-spontaneous if ΔG is greater than 0, and at equilibrium if ΔG is = 0. A reaction is favorable if ΔH is negative and/or ΔS is positive. When ΔH is negative and ΔS is positive, the reaction will be spontaneous. When ΔH is positive and ΔS is negative, the reaction will not be spontaneous. In any other situation, the result will depend on the values of H and S ΔG= ΔH-TΔS Living Systems are in a non-equilibirum state, meaning that most parts of the living system requires large -ΔS due to the need for molecules needing to be highly ordered Most ΔG for rxns in the living system are positive, non sponatenous, requiring energy. But though there are non-spontaneous rxns, there are still spontaneous rxns that drive the reactions froward. Reaction coupling is what makes this possible: ---Some steps in glycolysis have positive ΔG's, but other steps have very negative ΔG's. Those steps require the products of previous steps. Because the reactions are linked by the product of one reaction providing the substrates of the following reactions, the very negative ΔG's will pull the pathway forward, even though the positive ΔG's are earlier in the pathway than the very negative ΔG's.
Threshold Potential
This is the minimum stimulus that must be exerted upon the membrane to initiate the full action potential. It is usually reported as somewhere around -55 mV. If a stimulus depolarizes the membrane above this threshold, the entire action potential will follow. If not, the membrane potential will return to -70 mV.
Chemical Synapses
This is the traditional synapse you probably think of when you hear the word. It is the small gap between the terminal button and either: 1) the dendrite of a subsequent neuron, or 2) the membrane of a muscle or other effector. Calcium ions flood into the terminal button when action potential hits the end, they bond to proteins that keep AcH or Neutrotransmitters away from being released, allowing them to be released.
Hormonal Control: T3 & T4
Thyroid hormones that increase basal metabolic rate Secreted by thyroid in response to TSH from A. Pituitary Gland
Villi
Tiny finger-shaped structures that cover the inner surface of the small intestine and provide a large surface area through which digested food is absorbed The villi are finger-like projections of the wall of the small intestine. They are hollow and contain both blood vessels and a single lymphatic vessel called a lacteal. Fats are absorbed into the lymph system via the lacteals and carbohydrates and proteins are absorbed into the blood. The villi dramatically increase the surface area available for absorption.
Blood Typing
To avoid mistakes on blood-typing questions, always focus on the recipient. If a person's immune system sees any protein it does not have on its own blood cell membranes, it will attack it and coagulation/rejection will result. Thus, a patient with type A blood is fine with A antigens on donated blood cells, but will attack B antigens, whether from an AB, or a B donor. Type O blood can be donated to anyone because it has no A or B antigens. A person with blood type AB can receive from anyone because no donor will have any antigens this person's immune system hasn't seen previously. o Four phenotypes: A, B, AB, and O o The letters A and B indicate the antigens that are present on that individual's blood cell membranes: A = A antigens only B = B antigens only AB = Both A and B antigens O = Neither A or B antigens
Transferases
Transfer of a functional group (kinases, aminotransferases) move a functional group from one molecule to another molecule Three examples of these reactions are the activity of coenzyme A (CoA) transferase, which transfers thiol esters, the action of N-acetyltransferase, which is part of the pathway that metabolizes tryptophan, and the regulation of pyruvate dehydrogenase (PDH), which converts pyruvate to acetyl CoA.
Protein Folding
Translated Protein assumes Secondary structure almost instantly, then folds to globular or tertiary state. Various States: Globule- Fully Folded Molten Globule- Partially Folded Molten (Fully unfolded, denatured) It is driven by the following factors: Hydrophobic Core: -- Hydrophic r groups are interior to escape water. Hydrophilic Surface: -- Majority of R groups on surface or globular protein are polar or charged Electrostatic Interactions: -- Interactions between charged -R groups encourage folding and stabilize the folded state Hydrogen Bonds: --Hydrogen bonding with R groups stabilize folding Di-sulfide Bonds: --2 Oxidized cysteines forming a disulfide bond, strongest interaction Salt Bridges: --Formed when an acidic and basic -R group undergo a neutralization rxn resulting in salt. Proline Turns: -- Can be either distrupting or contributing to structure, but niether alpha helices or Beta sheets can contain proline internally iwthout distruption of the 2' structure. Solvation Layer: --A layer of water that surrounds a dissolved protein. These water molecules interact closely with each other and the protein's surface. The water that is in the hydration layer is more ordered that the bulk water in the general area and is considered not to participate with the unstructured bulk water Entropy and Protein Folding: --the driving thermodynamic force that favors protein folding results from the fact that non-polar regions require a much GREATER ordering of water molecules to accomplish solvation. Therefore, transitioning from solvation of non-polar regions to solvation of a mostly polar or charged globular protein surface, represents a net increase in entropy. In fact, it is enough to overcome the decreased entropy associated with the protein being in a folded rather than an unfolded state. This favorable increase in entropy is a major contributor to the overall conformational stability of the folded protein Remember, proteins are functional in stabilized form, NOT denatured form... so folded conformation is ACTIVE and unfolded, denatured, is INACTIVE
Translation
Translation begins when the small subunit attaches to the mRNA strand at the 5' end under the influence of various initiation factors. The small subunit scans the mRNA until it reaches the start codon, AUG. The first tRNA, which will always carry methionine and will have the anticodon 3' UAC 5' (to complement the start codon 5' AUG 3'), binds to the start codon along with the large ribosomal subunit (both ribosomal subunits are made up of rRNA plus some protein). The process up to this point is considered initiation. The complete ribosome then begins moving along the mRNA strand from 5' to 3'. There are aminoacyl (A), peptidyl (P), and exit (E) sites on the ribosome. New tRNA molecules carrying their associated amino acid enter at the A site driven by hydrogen bonding between the anticodon of the tRNA and the codon on the mRNA strand. A peptide bond then forms between the amino acid on the new tRNA and the amino acid on the previous tRNA, which sits in the adjacent P site. The new tRNA then shifts over into the P site and the previous tRNA enters the E site, dissociates from the protein, and exits the ribosome. Another new tRNA enters the A site and the process repeats. This entire process is called elongation. Finally, at some point, the ribosome reaches a codon on the mRNA such as UAG, which is a stop codon. There are no tRNAs that recognize and bind the stop codons. Instead a protein called a release factor binds to the stop codon and causes dissociation of the ribosome complex. This is referred to as termination. Where does translation occur? Cytoplasm and the rough ER and certain times on the mitochondria
Protein Hydrolysis
Trypsin and chymotrypsin cleave proteins on the CARBOXYL SIDE of specific amino acid residues: -Trypsin= Arginine, Lysine -Chymotrypsins= Phenylalanine, tryptophan, tyrosine
Gap Junctions
Tunnels between adjacent cells allowing exchange Points that provide cytoplasmic channels from one cell to another with special membrane proteins. Also called communicating junctions. occur between adjacent cells in many different tissues throughout the body. : 1) the junctions between cardiac muscle cells, or between smooth muscle cells, which allow for rapid passage of an electrical potential between cells 2) direct neuron neuron coupling found in certain parts of the brain and in the retina of the eye
Overall Energy Payout for Glycolysis and TCA
Two common errors are: 1) not considering the "net" ATP from glycolysis 2) ignoring the ATP required for the transport of NADH into the mitochondria).
Anatomy of the Long BOne
Two epiphyses (bulbous ends) cushioned by cartilage; the ends are filled with spongy bone and the shaft in between is made of compact bone; the center is a hollow cavity filled with yellow bone marrow.
T3 and T4
Tyrosine derivative and Lipid Soluble Function: Increases basal metabolic rate Organ that secretes it: Thyroid
Epinephrine and NOrepinephrine
Tyrosine derivative and Water soluble Function: causes resonses identical to sympathetic system of the flight or fight response Organ that secretes it: Adrenal Medulla
Epiglottis
U-shaped flap of cartilage and membrane oriented nearly in it's default position. THis allows air to proceed past it and into the trachea. Durign swallowing, this flap folds down over the opening portion of the larynx that contains the voice box and trachea, stopping food from entering the trachea, and thus leading food to the esophagus
Cancer:
Uncontrolled cell division due to failure of the cell's normal regulatory mechanisms.
Metabolism Locations
Understand locations of where metabolism and major biomolecules are at. Carbohydrates: Glycolysis= Cytosol Cytosol, pyruvates, PFK -1, PEP, Glycogen Synthase, transketolase/transaldose, citrulline, Ornithine Lipids= Metabolized in mitochondria, synthesized in Cytosol, modified by Smooth ER, Liver= GLuconeogensis, argininosuccinate (urea cycle), Mitochondria= ETC, PDH COmplex, Oxaloacetate, PDH Complex, alpha keto gluturate, Mitochonrial matrix- succinate dehydrogenase, citrate, carbamoyl phosphate, citrulline ,orinthine Inner mitochondrial membrane- alpha ketoglutarate, succinate dehydrogenase, ATP syntase ketolysis- heart, brain but not liver
Regulation of Carbohydrate Metabolism
Use common sense, the body doesn't want to over produce, it just wants to make the specific amount we need. Allosteric Control: 1st- Metabolic regulation involves DOWNSTREAM PRODUCT inhibiting an upstream enzyme. As the product builds up, the upstream enzyme will react with it, and the enzyme is inhibited. When the necessary amoutn needed is produced, there will be inhibition. 2nd- Target molecule is a major inhibited that downregulates upstream production. ex- When ATp acts an an allosteric inhibitor of PFK-1, the enzyme for the rate limiting step of glycoylsis. When ATP ↑, glycoylsis ↓. AMP and ADP are allosteric activators of PFK-1 3rd- Step most likely to be regulated is the first step, or 1st non-reversible rxn step. If pathway has multiple alt. pathways, the first irrerversible step is the regulatory point.
Minerals vs Vitamins
Vitamins are relatively small, organic molecules that are essential nutrients required in small amounts for proper metabolism. Many cofactors and coenzymes are derived from vitamins, such as NAD discussed in the previous question (derived from the vitamin niacin). We must acquire them through our diet. Water soluble vitamins are the ones most often required for synthesis of cofactors. Fat soluble vitamins are needed for diverse biological functions, such as vitamin A, which is converted to retinal and used as a coenzyme in visual proteins. Other fat soluble vitamins act as antioxidants, aid in maintaining blood pressure, and play a role in blood clotting. Nicotinamide Adenine Dinucleotide (NAD) 2Fe-2S iron-sulfur cluster Minerals are inorganic elements or compounds necessary for bone formation (calcium and phosphate), ion gradients (sodium and potassium), oxygen transport (iron-containing heme), muscle contraction (calcium), ATP processing (magnesium), production of stomach acid (chlorine), etc. Minerals are gained through diet and are needed in very small quantities, making them micronutrients.
Second Messenger Systems
Water-soluble hormones or signaling molecules bind to membrane receptors on the external surface of the plasma membrane. Only rarely does this binding initiate immediate and direct response in the target cell. More often, it initiates a cascade of events that magnifies the signal and, after multiple steps, stimulates the target cellular response. G-proteins are part of a very common second messenger system that has shown up on the MCAT multiple times
Neuron Signal Transmission at the Terminal Buttons
When an action potential arrives at the presynaptic membrane it triggers voltage-gated calcium channels to open, allowing calcium ions to flow into the cell. Inside of the terminal button are numerous neurotransmitter bundles—vesicles filled with neurotransmitter. The presence of calcium initiates a cascade that results in an exocytosis process wherein these bundles fuse with the presynaptic membrane, and dump their contents into the synaptic cleft. These neurotransmitter molecules diffuse across the gap and bind to protein receptors on the postsynaptic membrane. These receptors are usually associated with sodium channels so that the binding of neurotransmitter opens the sodium channel allowing sodium ions to flow into the cell. If enough sodium ions flow into the cell the voltage will reach the threshold stimulus and an action potential will be generated in the second neuron
What is nondisjunction and when can it occur? What are the ramifications?
When homologous chromosomes fail to separate during meiosis resulting in gametes with too many or too few chromosomes. Nondisjunction occurs when the chromosomes fail to separate properly during anaphase. This could be during meiosis I or II, or mitosis, although the scenario most commonly discussed is usually nondisjunction during meiosis I. Nondisjunction results in an unequal number of chromosomes in the daughter cells. When the daughter cell has an extra chromosome, this is an example of trisomy; when the daughter cell has just one chromosome, the condition is referred to as monosomy. Most cases of nondisjunction are fatal to the affected individual, but in a few instances nondisjunction can result in a viable offspring. For example, Turner's Syndrome is the result of monosomy of the X chromosome. The most common trisomic condition is trisomy of chromosome 21, known as Down Syndrome
The Large Intestine
Whenever you see "water absorption" or "vitamin absorption" THINK of the large intestine. In addition to absorbing vitamins from food, the large intestine also absorbs some vitamins produced by beneficial symbiotic E. coli bacteria that live in the large intestine (e.g., vitamin K, thiamin, riboflavin, and B12). A disease or illness that inhibits the normal function of the large intestinen will most likely result in diarrhea or constipation due to vitamin deficiency or problems with water absoprtion.
Anatomy of the Kidney
While the Nephron isn't specified in the picture, it is in the area where the renal pyramids are
Probabilities
You must be very confident in working with probabilities. They are frequently required to answer genetics problems and are an easy place to make errors. After reading the stem carefully you will only have 30-40 seconds to arrive at the correct answer, so you must be relatively fast as well. BOTH (AND): If both events must occur simultaneously, multiply the probabilities of each event occurring individually. EITHER (OR): If either event occurring fulfills the requirement, add the probabilities of each event occurring individually.
Endocrine Hormones
You need to know each hormone, it's function, whether it's a peptide, steroid, or tyrosine derivative, organ that secretes it, where that endocrine organ is located in the body Peptides are water soluble Steroids are lipid soluble and are all cholesterol derivatives Tyrosines (t3/t4= lipid soluble, epinephrine and Norepinephrine are water soluble) After you have memorized the entire chart, try to obtain a more conceptual understanding of each hormone in terms of how it acts, how it could be either inhibited or upregulated, and what physiological effects might result from either action. Notice that every gland (with one exception) secretes only one kind of hormone (steroid, peptide, or tyrosine derivative), but any given kind of hormone could come from various glands.
Vitamin E
a group of compounds that include both tocopherols and tocotrienols role as a fat-soluble antioxidant, disabling production of damaging free radicals in tissues an enzymatic activity regulator, for instance, protein kinase C (PKC), which plays a role in smooth muscle growth Vitamin E also protects lipids and prevents the oxidation of polyunsaturated fatty acids the picture is alpha tocopherol form of Vitamin E
Molecular Cloning: Plasmid and Gel Electrophoresis
a lab technique used to separate molecules by size. A mixture of molecules (usually nucleotide segments or proteins) is loaded onto a plate covered with an agarose gel. A charged field is created across the gel. Because nucleotides are negatively charged (due to the phosphate groups) they will be pulled through the gel toward the positive side of the field, which is called the anode. (IMPORTANT NOTE: The charge of the anode and cathode in gel electrophoresis is the exact OPPOSITE of the charges on the anode and cathode in galvanic cells). The gel acts like a molecular sieve, providing more resistance to the larger molecules. As a result, the smallest of all molecules travels the farthest, with all other molecules traveling a somewhat shorter path along a continuum down to the largest molecule. When a special kind of paper is placed on top of the gel, the separated molecules attach to the paper at their respective positions. This paper can then be exposed on a film to create a map of the separated molecules.
Myosin
a motor protein, not a microfilament A type of motor protein that associates into filaments that interact with actin filaments to cause cell contraction.
Inversion Mutations
a piece of DNA is accidentally cut out of a chromosome, gets turned around and is re-inserted into the gap upside down
Actin
a protein monomer that polymerizes to form microfilaments, MICROFILAMENTS ARE MADE UP OF ACTIN SUBUNITS
Menstrual Cycle
a recurring cycle (beginning at menarche and ending at menopause) in which the endometrial lining of the uterus prepares for pregnancy Begins with FSH, which stimulates the maturation of ovum and the follicle in the ovary (FSH also stimulates maturation of sperm in males). LH then stimulates cells in the ovaries to secrete estrogen (estradiol), which signals the uterine wall to proliferate and prepare for a potential pregnancy. Just before ovulation, a surge in the level of estrogen released causes a subsequent surge in levels of LH (luteal surge), which signals ovulation and the development of the corpus luteum. The corpus luteum begins secreting estrogen and high levels of progesterone to signal the uterine lining to prepare for implantation. If no fertilization occurs, the corpus luteum degrades and the menstrual lining sloughs off. If implantation does occur, the corpus luteum continues to secrete estrogen and progesterone, maintaining pregnancy.
Molecular Cloning: Vector
a segment of DNA used to transfer a desired sequence into another cell. Often, the vector is a bacterial DNA sequence such as a plasmid The target DNA sequence that researchers desire to multiply is added into the bacterial vector using restriction endonucleases. The vector can then be placed inside of bacteria and the bacteria cultured. Because bacteria reproduce exponentially, a huge number of new copies of the vector (with the target sequence included) can be created in relatively little time
Lytic Cycle
a viral reproductive cycle in which copies of a virus are made within a host cell, which then bursts open, releasing new viruses The lytic cycle of a virus is the period during which viral genes are actively transcribed and new viruses are assembled. During this phase, infected cells eventually burst to release large numbers of new viruses. Examples would be an active cold sore (herpes virus) or AIDS
Effects of Local Conditions on Enzyme Activity
a) All enzymes have an optimal pH at which enzyme activity is highest. For most enzymes this is around 7, but the optimum pH can vary based on typical pH for that enzyme's environment. Pepsin, for example, has a pH optimum of about 2 (the normal pH of the stomach). Enzymes in lysosomes will also prefer a lower pH, as will the enzymes of acidophiles. Whatever the optimum is, movement in either direction causes a rapid decrease in rate because changes in pH will affect the hydrogen bonding of the enzyme itself, possibly altering the structure, and will likely disrupt the enzyme-substrate complex. b) Mildly increasing temperature will increase the rate of an enzyme catalyzed reaction. However, increasing the temperature too much will denature the enzyme, causing the reaction rate to drop precipitously, (Think of yeast) c) At low substrate concentrations, the reaction rate will increase rapidly. As more and more substrate is added, the rate increase will drop off, due to the enzymes being fully saturated d) Enzyme concentration shows a "saturation curve" similar to that for substrate concentration and similar logic applies. Adding enzyme when enzyme concentration is low will increase the rate, because there is plenty of substrate available for the newly added enzyme molecules to act upon. As saturation levels are reached, the rate increase will drop off because enzymes are less and less likely to encounter a substrate molecule.
Q37. If the following pairs of circumstances both exist within a bacterium, determine whether or not the Lactase gene will be transcribed: a) glucose, no lactose, b) lactose, no glucose, c) no glucose, no lactose, d) lactose and glucose
a) no transcription (inhibitor would be bound) b) yes, gene is transcribed; c) no transcription (inhibitor would be bound) d) no transcription (or very little; inhibitor would not be bound, but cAMP levels (the activator) will be low when glucose is present).
Structural Proteins
actin (thin filaments, microfilaments), tubulin (microtubules), keratin (hair and nails, intermediate filaments), elastin (connective tissue, extracellular matrix).
cholesterol
an amphipathic molecule with a steroid region and a polar region. It is inserted between phospholipids at very high concentrations in eukaryotic cells. It serves a dual purpose, both adding rigidity and fluidity to the membrane. At higher temperatures, around normal physiological conditions (37°C), the non-polar region of cholesterol interacts with the hydrophobic tails of the phospholipids helping to hold them in place and thereby adding rigidity to the membrane. PRE CURSOR FOR ALL STEROIDS The polar region of cholesterol also interacts with the polar phosphate heads. However, at lower temperatures, when the interactions between the non-polar tails could cause crystallization, the presence of the rigid steroid portion of cholesterol disrupts Van der Waals forces between fatty acid tails maintaining a minimum level of fluidity
Trypsin
an enzyme from the pancreas that digests proteins in the small intestine proteases that cleave peptide bonds at specific amino acid sequence
Telomerase
an enzyme that adds length to the telomeres Q30. Telomerase is active in somatic cells early in development, but is turned off in somatic cells thereafter. Why would a mature somatic cell with telomerase activity be potentially harmful? -Unlimited cell division= BAD Because telomeres are shortened by each round of cell division, they provide somewhat of a "time clock" for cells. After the telomeres are gone, subsequent division will quickly damage important coding sections of the DNA. Presumably the cell could not survive very many additional divisions without being directed into apoptosis. This would act to prevent the uncontrolled cell division found in tumors. However, if the enzyme telomerase were present, the cell could replace the telomere as it was being used up—essentially removing the "clock function" of the telomeres and theoretically allowing for unlimited cell division
Autotroph
an organism that is able to form nutritional organic substances from simple inorganic substances such as carbon dioxide. Autotrophs are capable of fixing CO2 and can therefore use CO2 as their carbon source for synthesizing organic molecules.
membrane receptors
any protein that specifically binds a signaling molecule (i.e., ligand) that initiates a cellular response. Steroid- hormone receptors are located inside the cell, often in the nucleus, as steroids can diffuse through the hydrophobic membrane core, while receptors for all polar ligands are located on the external surface of the membrane
Cancer: Proto-oncogenes
are "good" or "normal" genes that can become oncogenes (i.e., cancer-causing genes) if mutated; proto-oncogenes usually regulate cell division, cell cycle, growth, apoptosis, etc. as their normal function. It is therefore logical to see how they could cause cancer when mutated.
Spindle Apparatus
array of microtubules that grows outward from the centrioles during mitosis to bind with the centromere of the chromosomes at the metaphase plate This assembly effect division of a pair of sister chromatids into two separate chromosomes
Neurulation
at about week 3, the notochord forms from the mesoderm and induces the overlying ectoderm to form the neural plate, which becomes the neural tube and eventually the spinal cord. https://www.youtube.com/watch?v=dAOWQC-OBv0
HARDY-WEINBERG Equilibrium
condition that occurs when the frequency of alleles in a particular gene pool remain constant over time The MCAT may very well ask you to conceptualize how H-W predictions will vary from real life. 1) Large population 2) No mutation 3) No immigration or emigration 4) Random mating 5) No natural selection
Amphipathic Lipids
contain polar(hydrophilic) and non polar (hydrophobic) regions, Amphipathic molecules have both hydrophilic and hydrophobic properties (think of amphibians that live in both water and on land). They have both polar and non-polar structures. Amphipathic lipids are found in lipid bilayers, with the polar head groups on the surface and the non-polar tails within the membrane. following are amphipathic: fatty acids (carboxylic acid is polar), phospholipids (phospho group is polar), sphingolipids (oxygen and nitrogen are polar), and glycolipids (oxygens of the sugar are polar). Triacylglycerols, steroids, terpenes, and waxes are hydrophobic and not amphipathic.
Proximal Convoluted Tubule
first section of the renal tubule that the blood flows through; reabsorption of water, ions, and all organic nutrients The proximal convoluted tubule (PCT) is the section of the nephron between Bowman's capsule and the descending limb of the Loop of Henle. Along the PCT sodium is reabsorbed via active transport, and glucose is reabsorbed via secondary active transport through a symporter identical to the one used to absorb glucose from the small intestine. Water follows the solutes via facilitated diffusion. However, because water and solutes are reabsorbed in the same ratio, the filtrate remains isotonic (i.e., the volume of filtrate decreases, but its concentration remains constant)
The 9+2 arrangement
found in eukaryotic cilia and flagella
Evolution & Populations: Gene Pool
gene pool is the complete set of genes and alleles in a population
Intermediate Filaments
general class of several proteins that polymerize to form filaments that are intermediate in diameter between microfilaments (the smallest) and microtubules (the largest).
chromatin
general term for DNA and protein. Therefore, chromosomes are made up of chromatin. Heterochromatin is highly condensed DNA, wrapped around histones, which is in accesible
Cancer: Tumor Suppressor Genes
help protect the cell form uncontrolled growth. When function of such a gene is lost the cell is more easily able to become cancerous. Tumor suppressor genes require two recessive alleles to lose function. Oncogenes, however, are generally gain-offunction alleles and therefore having only one bad copy can result in the undesired cancerpromoting protein. Most cancers follow the "two-hit" or "multiple hit" hypothesis. In other words, multiple mutations must accumulate before the cell becomes cancerous. For example, a proto-oncogene could be mutated, but the cell might not become cancerous because of the action of a tumor suppressor gene. If the tumor suppressor gene lost function (the "second hit") then the cell would become cancerous.
Voltage-Gated Potassium Channels
integral proteins that respond to a change in the membrane potential. However, their threshold for responding is much higher than that for the voltage-gated sodium channels. As a result, they only react following the very large change in membrane potential caused by depolarization. Just before maximum depolarization is reached, the Na+ channels begin to close and the K+ channels begin to open. At point 3, they open and sodium closes.
transport proteins
integral proteins that span the entire width of the bi-layer membrane (i.e., transmembrane proteins) creating tunnels for the passage of ions, proteins, or other substances through the hydrophobic core
Genetic Regulation: LAC OPERON
lac operon (lactose operon) is an operon required for the transport and metabolism of lactose in Escherichia coli and many other enteric bacteria. Although glucose is the preferred carbon source for most bacteria, the lac operon allows for the effective digestion of lactose when glucose is not available. Specific control of the lac genes depends on the availability of the substrate lactose to the bacterium. The proteins are not produced by the bacterium when lactose is unavailable as a carbon source. The lac genes are organized into an operon; that is, they are oriented in the same direction immediately adjacent on the chromosome and are co-transcribed into a single polycistronic mRNA molecule. Transcription of all genes starts with the binding of the enzyme RNA polymerase (RNAP), a DNA-binding protein, which binds to a specific DNA binding site, the promoter, immediately upstream of the genes. Binding of RNA polymerase to the promoter is aided by the cAMP-bound catabolite activator protein The first control mechanism is the regulatory response to lactose, which uses an intracellular regulatory protein called the lactose repressor to hinder production of β-galactosidase in the absence of lactose The second control mechanism is a response to glucose, which uses the catabolite activator protein (CAP) homodimer to greatly increase production of β-galactosidase in the absence of glucose https://www.youtube.com/watch?v=LuOaEe89_HE
Semi-discontinuous
one strand (leading brand) is synthesized continuously and the other strand (lagging strand) is synthesized in okazaki fragments (discontinuous)
Thymine (T)
pairs with A via two hydrogen bonds
Guanine (G)
pairs with C via three hydrogen bond
Cytosine (C)
pairs with G via three hydrogen bonds
Adenine (A)
pairs with T via two hydrogen bonds
Dendritic Cells
professional antigen-presenting cells. They efficiently phagocytize pathogens and present those antigens on their surface to stimulate other immune cells. Dendritic cells are white blood cells (leukocytes), but are not lymphocytes. They can form from monocytes (which also differentiate into macrophages) or independently in their own cell line from a blood cell precursor. Their main function is to process antigen material and present it on the cell surface to the T cells of the immune system. They act as messengers between the innate and the adaptive immune systems.
M-M Equation
relationship between velocity, Km, and substrate concentration v= (Vmax [S])/(Km + [S])
Renin-Angiotensin-Aldosterone System
responsible for regulating blood pressure. stimulated by low blood pressure or certain nerve impulses, the kidneys release an enzyme called renin. this triggers a signal transduction pathway: renin splits the protein angiotensinogen, producing angiotension II. You don't need to memorize it, but understand the main concept of this pathway
Antibody Structure
the N-terminus and C-terminus of each chain—emphasizing that these are protein chains. Antigens bind to the ends of the hypervariable regions. An antigen would contact both the end of the heavy chain and the end of the light chain. The shapes of antibody binding sites are NOT determined in response to the shape of foreign antigens. They are determined by the individuals' genes. Antibodies are made by random splicing of gene products in a way that provides huge numbers of receptors each with a unique shape. Due to the sheer number of antibodies, almost any antigen will happen to match one of the existing antibodies. Although the creation process is random, antibody-antigen pairing is specific: one antibody will bind only one antigen. A favorite MCAT principle is the fact that antibodies are never created "in response to" or "to match" antigens. Antibody creation is a random process. The sheer number of antibodies created, coupled with a somewhat flexible binding requirement, ensures that a foreign antigen will be bound by a host antibody ANTIBODY/PRIMARY/SECOND RESPONSE= HUMORAL
Coding Strand
the strand of DNA that is not used for transcription and is identical in sequence to mRNA, except it contains uracil instead of thymine
Anti-Coding Strand
the strand of DNA that the Poly reads. Opposite of the RNA transcript The anti sense strand
Molecular Cloning: Hybridization
therefore any two fragments can hybridize, or join together to form a single strand.
Scrotum
thin sack of skin in which the testes are located. The external location of the scrotum allows the testicles to exist at a temperature a few degrees lower than the normal human body temperature of 37°C. The optimum temperature for spermatogenesis is 35°C
Ejaculation Pathway
vas deferns, ejaculatory duct, urethra During ejaculation, sperm leave the epididymis via the vas deferens. The vas deferens arches back up into the pelvis and then back down toward the penis. Along the way, the seminal vesicles, prostate gland and bulbourethral gland (a.k.a. Cowper's gland) all secrete various lubricants and nutrients into the ejaculate. The vas deferens empties into the urethra at the base of the urinary bladder. The urethra then travels down the penis During ejaculation, the first addition to the ejaculate comes from the seminal vesicles. They release the majority of the fluids that make up semen, including fructose and alkaline fluids that make the semen basic. The alkaline nature of semen helps neutralize the acidic environment of the vagina and the fructose provides nutrients for the sperm. The vas deferens continues into the prostate gland, which secretes a milky white fluid that is slightly acidic and contains proteases. The prostate gland secretions play a protective role, as sperm have been shown to have longer survival rates and better protection of their genetic material in the presence of prostate secretions as compared to without them. The vas deferens then releases its contents into the urethra where it passes the bulbourethral glands (a.k.a., Cowper's glands). The bulbourethral glands do not add fluids to the ejaculate at this point. They secrete a fluid called pre-ejaculate that lubricates and neutralizes any acidic urine in the urethra prior to the arrival of the other semen components. The term semen refers to the entire ejaculate with all contributed fluids plus the sperm.
Eukaryotic Flagella
whipping motion; microtubules made of tubulin Larger and COmplex structure, 9+2 arrangement ATP Driven
Standard Free Energy Change (ΔG°') and the Equilibrium Constant (Keq)
ΔG°'= -RTlnKeq At equilibrium, Q = Keq and ΔG = 0. Starting with: ---ΔG = ΔG°' + RTlnQ we have ---ΔG = ΔG°' + RTlnKeq and then ---0 = ΔG°' + RTlnKeq. ---Subtracting RTlnKeq from both sides, we get ΔG°' = -RTlnKeq If Keq = Q, the reaction is at equilibrium, and ΔG = 0.
Estrogen and Progesterone Levels:
• If hormone levels go up unexpectedly, high levels could cause unexpected menstruation if— and only if—that increase was followed by a sudden decrease. It is the drop in hormone levels that causes menstruation. Unexpected menstruation of this type can sometimes be seen in elderly women given estrogen/progesterone therapy for treatment of osteoporosis. • For menstruation, or the sloughing off of the uterine lining, to occur, there must first be a build-up of that lining. Buildup and maintenance of the uterine lining are normal functions associated with estrogen/progesterone (see the Hormone Chart in Biology 2). • Do NOT confuse menstruation with ovulation. Ovulation requires a surge in hormone levels. Menstruation requires a chronic decline. • Persistent low levels of estrogen/progesterone lead to the symptoms of menopause described below.
Role of Liver in Glucose Metabolism
• In response to low blood glucose levels, alpha cells in the pancreas secrete glucagon. • Glucagon stimulates glycogenolysis in the liver—the breakdown of glycogen stored in the liver to form free glucose for release into the blood. • In contrast, high blood glucose levels stimulate beta cells in the pancreas to secrete insulin. • Insulin stimulates glycogenesis in the liver—the synthesis of glycogen for storage in the liver. - Insulin also stimulates the uptake of glucose from the blood into the cells. Finally, the liver converts lactate, glycerol, amino acids, and some TCA-cycle intermediates into glucose, main process is called GLUCONEOGENISIS Increased Glucagon = Increased glucose in blood, break down from glycogen Increased insulin= increased storage of glucose to glycogen
Order of Deprotonation
• Proceeding from acidic to basic (low to high pH): 1) -COOH Group pKa ~ 2 2) -R Group, ACIDIC pKa ~ 4 [Asp = 3.7; Glu = 4.5] 3) -R Group, His pKa ~ 6 4) -NH3 + Group pKa ~ 9 5) -R Group, BASIC pKa ~ 11-12 [Lys = 10.7; Arg = 12]